Tips to Use Crystal Maiden (Dota2)

• Crystal Nova is a large area of effect nuke that also slows your enemies. You can hit enemies from 1100 units away with it (700 casting range + 400 radius).

• Frostbite is a great disable which prevents the target from moving or attacking. It also interrupts channelling spells and teleports. Unfortunately, it does not prevent enemy heroes from casting spells.

• Arcane Aura used to be prioritized as it benefits the whole team greatly, especially one with a strong caster/ganker line-up. But the introduction of Arcane Boots has made this skill somewhat less useful.
  • Since 6.76 this bonus is doubled on Rylai herself, granting a whopping +5 bonus mana/s.

• Freezing Field is an incredibly strong spell. However, it can be unpredictable and usually gets interrupted by your enemies very quickly. Freezing Field consumes a lot of mana, so use it sparingly.
  • Many players choose not to skill Freezing Field until quite late in the game, as it is a situational spell that is most effective in large clashes; and its use consumes a huge amount of mana. However, its slow and gigantic (if unpredictable) damage can be very useful in early game, especially against enemies that lack the means to interrupt it. Let your decision be informed by enemy lineup as well as laning composition.

• Items like Black King Bar and Shadow Blade are viable options to prevent your opponents from cancelling your ultimate, but Crystal Maiden usually won't have that much gold to spend.

• Crystal Maiden can either babysit her team's carry on dual/triple lanes, or roam between the lanes to gank enemies.

• Always ward the woods. Wards should be bought over and over again to provide map control through the whole game.

• There is a temptation to use Crystal Nova to push lanes, but owing to its mana cost and long cooldown this isn't a good idea.

• If you have a few coins to spare - always buy items that boost your survivability, or get yourself an escape/positioning mechanism like Blink Dagger or Force Staff.

• Freezing Field must be used at the right time to avoid interruption and being focused. Generally speaking, in an encounter it is best used after the initial nuking phase; when the enemy's stuns are on cooldown (building a Black King Bar will provide immunity to stuns; but Crystal Maiden does not typically get much gold and this can be very difficult to build in a game where your team is not getting a lot of kills). If your team has an initiator with the capability to disable a group of enemies, such as Tidehunter or Enigma, Freezing Field should be used in synchronisation with their mass disable. Using Freezing Field very often results in Rylai's death, and she rarely is able to channel it for its full duration, but if she can maintain it even for a few seconds it will be useful for her team.
  • Although Freezing Field's damage can be upgraded with Aghanim's Scepter, its primary use is its slow rather than its damage and considering Rylai's low gold income, building Scepter is typically not a good idea; her ult would be more useful if instead she built Black King Bar and/or Blink Dagger and typically of a support hero she normally must choose only a couple of luxury items. 
   

source: http://dota2.gamepedia.com/Crystal_Maiden

Tips to Use Luna (Dota2)

• Luna and Night Stalker complement each other well; as Eclipse causes day to become night and Darkness gives both of them a very long vision range.

• Early points in Lunar Blessing will make last-hitting creeps easier. At any rate, make sure you have a single point in it before the first night as only one point is needed for the full amount of vision it bestows.

• Early points in Moon Glaives will push the lane. Moon Glaives is commonly not skilled at all until the laning phase has concluded.

• Extremely unusually for a hard carry, Luna gains significant killing power with a level advantage, owing to Lucent Beam and by extension Eclipse.

• Lucent Beam's cast range is gigantic. Use it to pick off fleeing heroes.
  • Bear in mind Eclipse's range is much smaller than Lucent Beam's.

• Under almost all circumstances Luna should be paired with a disabler for her laning phase; as aside from her high movement speed she has absolutely nothing to help her avoid ganks or kill attempts.
  • It takes significant skill and knowledge of the game to solo a lane with Luna. Her very small attack range and purely damage-oriented skillset mean she is extremely easy to kill. Even then, it is recommended to have ward vision and easy access to team backup for her to be successful in a solo lane. The advantage of running a solo Luna is that it is essentially high-risk high-reward. A Luna with level advantage doing well can easily set the momentum of the game in her team's favor. 
   

source: http://dota2.gamepedia.com/Luna

Tips to Use Bane (Dota2)

• Between levels 6-12 Bane is comparatively a very powerful hero, and assuming you maxed his Brain Sap (as you should under all circumstances) you will be able to solo most heroes by means of Fiend's Grip followed by Brain Sap. It is necessary to get kills during this phase of the game; as if Bane is not well-geared and leveled up later in the game, he will be relegated to a support unit.

• It is important for the player to judge when to change roles; as mentioned above, Bane should gank constantly in the middle of the game to gain a gold advantage and avoid getting shut down or subjugated to a conservative support role. A well-managed Bane can change the outcome of a team fight in the late game with effective use of items such as Necronomicon, Scythe of Vyse, and Aghanim's Scepter.

• New or unseasoned players have a tendency to attack targets under Nightmare. Before the game starts, make sure to warn them about it.

• Bane is not an initiator; despite having two disables, he is far too delicate to withstand the initial retaliation. Instead, he should hide until such time as his abilities become crucial when the team fight has ensued(preventing escapes, finishing off enemy heroes with Brain Sap, etc.).

• Avoid heroes with stuns, as they can interrupt Fiend's Grip. If you must deal with them, incapacitate them via Nightmare, a Scythe of Vyse, or Fiend's Grip itself. Picking Bane in a match against several heroes with disables is unwise. Black King Bar is typically an effective first major item to build on Bane if you need to help your team disable someone before they retaliate.

• If the enemy team lack area-of-effect stuns or interrupts, a Shadow Blade can make your ultimate harder to stop, since your opponents must first reveal you and then interrupt you. As with all similar abilities, you can activate invisibility without breaking your channel. While Shadow Blade is also effective for ganking solo heroes and escaping, you should still get Black King Bar instead if the enemy team have ranged AoE interrupts such as those possessed by Lina, Drow, Dark Seer, Death Prophet etcetera. 

source: http://dota2.gamepedia.com/Bane

Tips to Use Faceless Void (Dota2)

• Mask of Madness will allow Faceless Void better to utilize Chronosphere throughout game, as does almost any item that gives attack speed or damage. A BKB is usually a good choice after getting a MoM as nukers outside the chronosphere can be ignored, while they otherwise burst the fragile Void very easily.

• When using Chronosphere it's important that you prioritize the targets to deal maximum damage. Important targets include carries and spellcasters.

• If you want to play your lane aggressively rank up Time Lock first, conversely if you need to play defensively rank up Backtrack after getting at least one rank of Time Walk as it is still your primary escape mechanism, while also having some offensive potential.

• Chronosphere will pause friendly units (exception : units under control of Faceless Void) and heroes as well as foes. Try to position it so enemies are within the sphere and allies are outside and can reach enemies inside without having to enter Chronosphere itself.

• Using later ranks of Time Walk and Chronosphere in tandem can easily catch entire enemy teams off guard.

• Although Faceless Void is a hard carry hero, he is extremely supportive when using his Chronosphere as it has the potential to trap the entire enemy team in place for many seconds, allowing easy use of several ranged ultimates altogether for massive damage. Example: Lich, Jakiro, Witch Doctor and Gyrocopter ultimates.

• If you are trying to decide on what item build is best for Faceless Void remember that his main goal is to do the most damage and hopefully kill at least one key enemy hero inside his Chronosphere where he has a 5 second free reign to attack a target without any chance of retaliation.

• While Aghanim's Scepter may diminish your carry potential sometimes it might come in handy as it increases your Chronosphere duration to 6 seconds and reduces its cooldown to only 60 seconds, allowing your ultimate to be ready in almost any team fight and while it may not contribute to your damage output very much it does increase your survivability by granting you stats and HP. 

source: http://dota2.gamepedia.com/Faceless_Void

Tips to Use Undying (Dota2)

• One of the best skills to use early game is Decay: it's quite spammable, and will make ganking easier. You can easily get first blood if you're laning with a good partner.

• Decay is very useful even if left at level 1. Max it when team battles begin to start: you can spam it even more and make enemies squishier.

• Undying can be played in many ways: if you're going for a more supportive role, use your Tombstone and your Flesh Golem to slow the enemies while spamming Decay, then let your lane partner get the kill. Otherwise, use Soul Rip to finish a Hero while there are many creeps nearby: this way it will deal more damage.

• Don't use Soul Rip to harass, but use it to heal a friendly hero or to finish off enemies. This is more effective if there are many units nearby, such as creeps if you're laning, or heroes if you're initiating.
  • Remember that Soul Rip can be used to heal your tombstone.

• While initiating, use Tombstone and Flesh Golem, then Decay/Soul Rip: this way these skills will deal more damage.

• Though his spells are individually quite cheap, you will almost always have mana problems since both Soul Rip and especially Decay are very spammable. Consider getting Arcane Boots during the laning phase, then disassembling it once you have enough to buy the remaining pieces of a Bloodstone. You can then convert your standard boots to Phase Boots allowing you the mobility and chase power to keep Flesh Golem's powerful aura on the right targets during a teamfight.

• Another good item for Undying in the early game is Soul Ring. After using Soul Ring, you can cast decay for free. If you hit 2 or more Heros with this spell, you make up for the HP cost for Soul Ring.

• If you don't have enough money to buy a Bloodstone in time or you'd prefer cheaper items, try to make yourself as tanky as possible: if you're initiating, enemies will target you first. That's why you need an early Vanguard and/or a Hood of Defiance if the opposing team has a lot of nukers. Other useful items that increase your HP are Rod of Atos, which will probably solve most of your mana problems too, and Heart of Tarrasque.

• Should the enemy team have an Earthshaker, it is unwise to place a tombstone at the beginning of a teamfight. Each zombie will cause the echo to deal extra damage, likely obliterating your entire team (or at the very least severely injuring them).

• Zombies are magic immune, but will take full damage from AoE physical abilities. Be aware of heroes with these abilities that can easily deal with your Tombstone zombies, such as Gyrocopter's flak cannon, Axe's counter helix or Bristleback's quill spray.

• If Naga Siren is on your team, be aware that Tombstone will summon zombies even when the enemy targets are sleeping and untargetable. This can be used to your advantage

source: http://dota2.gamepedia.com/Undying

Tips to Use Tidehunter (Dota2)

• Blink Dagger is a commonly built item on Tidehunter, used in conjunction with Ravage to initiate.

• Anchor Smash is a great way to clear creeps and farm for Tidehunter. Due to its low Mana cost, it can be used to harass enemies, especially melee heroes.

• Do not underestimate the 40% damage reduction from Anchor Smash. If you use it on a hero with a powerful auto-attack, such as Ursa, their damage output will be severely reduced. With 100% uptime from level 2 onwards, you can keep one or more enemies' attack damage crippled indefinitely provided you keep using this skill.

• Resist the urge to take early levels of Kraken Shell for the block during the laning phase. Tidehunter's two other abilities both scale very well with additional ranks, and if you need damage block you can simply buy a Stout Shield and sell it later for minimal (125) gold loss.

• Remember that while Ravage travels quickly, it does take a brief time to extend to its maximum range. Very alert opponents might be able to blink away or activate magic immunity before they are stunned, so be sure to blink in closer to those heroes to reduce their window of escape.

• Extremely quick fingered opponents may also avoid Ravage by blinking very close to Tidehunter, a small area around Tidehunter exists in which Ravage will not affect very close opponents.

• Should the enemy team have a Rubick, it is critically important to cast another one of your spells (generally anchor smash) after casting ravage, as a skill so devastating could easily be the deciding factor in a teamfight should Rubick steal it. 

source:  http://dota2.gamepedia.com/Tidehunter

Tips to Use Morphling (Dota2)

• As Morph gives +3 to both Agility and Strength with one level, it's a very strong skill to get at level 1.

• As Adaptive Strike scales with stats, it shouldn't be leveled until after Waveform is maxed and should be the last skill maxed out.

• Boots of Travel is a commonly built item on Morphling. By using Replicate, then teleporting back to base, you can then instantly return to where you were with Morph Replicate. This strategy can also be used with Town Portal Scrolls.

• Ethereal Blade is the most common and recommended item for burst damage on Morphling. By Morphing points into agility, he can cause massive damage with Ether Blast, and then use the amplified magic damage to finish an enemy off with Waveform and Adaptive Strike. This is sometimes referred to as the "Shotgun combo". However, do not build ethereal blade if Morphling lacks farm, as this item is most effective midgame, building it too late would not be useful.

• Sometimes deciding which hero to choose for Replicate can be difficult, however potential candidates for this spell include: a hero with high DPS, those with favorable passives (such as Axe's Counter Helix) or even an enemy hero who has a Radiance or some other aura, which allows you to take advantage of receiving its effects for free.

• It can be difficult to determine whether a Morphling illusion is real because it does not take any bonus damage unlike every other illusion in the game. You can use this to try and fool opponents into blowing long cooldowns.

• Morphling's early game damage is relatively high with Waveform and decent right click through Morph Agility Gain. Consider laning with an aggressive support to grab some early game kills so you can accelerate your farm and reach your late game faster.

• Morphling functions better as a carry in teams with a strong front line. This allows him to remain in the fight with a high amount of agility and hence right click or Adaptive Strike damage, without feeling the pressure of being focused. Although he is good at soaking damage through Morph Strength and items such as Linken's Sphere and Eye of Skadi, he is much more useful as your team's primary source of consistent damage. 

source: http://dota2.gamepedia.com/Morphling