Light Up The World (And Your Enemies)

Ezalor, The Keeper Of The Light

General Look at Ezalor

This guide will show you a decent way to play Keeper, as he works with most any character. As a combination of a pusher, nuker, and support. He can play each role quite effectively when built and played correctly, so you don't have to worry much about holes in your team (too many carries, ****ty supports, etc.)

Abilities

1. Illuminate

This is your main attacking and pushing ability, but it is a channeled ability which can be released at any time. The damage and range scales with the amount time charged, and with good timing you can deal quite a bit of damage.

Range: 230
Radius: 400 (starting radius), 800 (distance), 400 (final radius)
Maximum channel damage: 200/300/400/500
Cooldown: 10
Mana: 150

2. Mana Leak

Useful ability against nukers and those who rely on mana, and is also good for to use against those who try to pull back or retreat. Also fun during the laning phase if going against either supports or pushers to keep them docile.

Range: 550/700/850/1000
Duration: 4/5/6/7
Percentage of maximum mana drained per 100 units the target moves: 3.5%/4%/4.5%/5%
Stun duration: 1.3/1.6/1.9/2.2
Cooldown: 18
Mana: 75

3. Chakra Magic

Possibly the greatest support/survival ability in prolonged teamfights. Provides large amounts of mana in a short cooldown to the targeted unit. Not suggested to restore mana on creeps, though, you and your team need that more than anything. Takes some knowledge of other characters to know whom to give mana too, so watch how you spend your chakra charges.

Range: 900
Mana restored: 75/150/225/300
Cooldown: 19/18/17/16
Mana: 40/55/70/85

4. Spirit Form

An interesting ult, allowing to charge an illuminate without having to channel it yourself (done by a separate spirit) and unlock two new abilities, Recall and Blinding Light.

Duration: 40
Cooldown: 80/70/60
Mana: 100

Recall

A global teleporting spell that brings an ally to you after a short duration. If they take any player based damage, however, the ability is cancelled. Useful for saving heroes on the run, but hope that they don't get hit by the enemy; and for bringing in a teammate for a save/gank/teamfight/general transport.

Range: Global
Teleportation delay: 5/4/3
Cooldown: 15
Mana: 100

Blinding Light

A huge AOE blind and knockback, a very useful ability for near any situation. Saving running teammates or yourself, or for knocking the enemy closer to be ganked, or knocking them in the way of your Illuminate (difficult to do if the enemy is fast). The miss chance the blind causes is also great for starting ganks or teamfights, as they'll be helpless.

Range: 900
Radius: 675
Miss chance: 80%
Duration: 3/4/5
Cooldown: 20/16/12
Mana: 50

Luminescent Teamwork

Because of his Chakra magic and general supportive nature, Ezalor makes for a great teammate, provided you know what your doing. Some of the heroes that Keepers works with best (not always ones in need of mana) are:

1st Choice - Best/Constant Cooperation

Pudge is a double edged cleaver. On one hand, his ult has a low coodown and a massive channeled stun. His hook also allows for those who run to be pulled right back into your Illuminate, and stun them when they're affected by Mana Leak. But the downside is Pudge's abilities require a lot of mana, and seeing as how they are cast quite often, you will be providing most of your Chakra Magics to him. (NOTICE) - When roaming with Pudge, focus on acquiring Force Staff and Eul's Scepter Of Divinity, to boost your mana and set up attacks for Pudge.
Chaos Knight is great for keeping the enemy in one spot while you charge up your Illumate, and most of the time you can get a full 5 second charge out of it, depending on the hero you're trying to kill. His ult can be used to block enemies somewhat as they try to get away, but that requires more attention from CK, and that could be detrimental in a teamfight. You may also find that with his mana dependence and the fact he will spam his abilities, that you are giving him quite a few Chakra charges.
Her Ensnare is your best friend for BKB'd targets, and she can make herself a meat shield with her illusions. The Song of The Siren ult is one of the best for you, as it can allow you to either charge another shot or escape, or bring more teammates in. The ult just gives you time to do anything you need to. Be warned though, as a good Siren will go through her abilities quite a bit, thus a lot of mana. So be sure to keep her nice and charged up on that.
His stun and mana dependence have a void in them, one that Keeper fits perfectly. Sand King's duststorm (if used correctly) can push the enemy right into an Illuminate, though this requires plenty of vision and timing. But as long as you can coordinate your Illuminate with his stun, you shall be just fine. Watch out though, as you might find Sand King will be taking most of the Chakra charges.
Bane. His stuns allow for Keeper to charge up his illuminate to kill the target quite easily, and prevents damage to the Keeper by Bane's Enfeeble. A similar thing occurs with Bane as with Pudge, but to a lesser degree as Bane is an intelligence character. Give him most of your Chakra charges, but watch your mana to make sure you don't run out.
Sven is a great combo with Keeper, as Sven is dependent on his mana, and Keeper can fill him up in 1 Chakra. Sven's stun time with Illuminate creates havoc with the target(s), usually leading to a kill. Warcry can also make Ezalor faster than he already is. And similar to Sand King, Sven will probably be taking most of the Chakra charges.
His Sprout at lvl 4 is a guaranteed full Illumnate charge, as the cage lasts 5.25 seconds. His teleport can also (and usually is) used to kill the runners, which is exactly what your Illuminate will create. With masses of his treants, he can surround the enemy(s) so you can charge up properly.

2nd Choices - Limited Cooperation

His stun is pretty useful, and can allow for you to charge Illuminate to pretty lethal levels. His mana dependence can also create a follower out of him.
His constant stuns are always helpful for Illuminate, but the fact he works best dashing into a fight, only work with him when he attempts a charge or is in trouble.
Dark Seer depends on the situation, but is usually a good choice. Ezalor can keep swift with DS's speedy Surge, and his Vacuum can allow for all the heroes in the area to be affected by Illuminate. Again, him being an Intelligence hero, he regenerate mana rather quickly, though he won't need much Chakras except in prolonged ganking/teamfighting.
Venomancer slows the enemy, preventing them properly escaping from Illuminate. Venom will be focused instead of you in teamfights, you can Mana Leak the nearest enemy nuker, or use Blinding Light to save Venomancer if he gets into trouble. As Venomancer mostly uses his auto-attack for fighting, you'll only have to give him mana to initiate, or perhaps to finish an enemy off. The rest of the time, they should be just fine.
Slardar provides tons of stuns with lots of speed, ideal for lining up the way for Illuminate, and the Chakra Magic will serve Slardar well, his low mana costs help. Most of the time, however, you'll want to Chakra yourself or someone who needs it, Slardar is medium on the list.
Viper works the same reason as Venomancer, but require a bit more chakra charges than Venom would because of is auto-cast ability and Viper Strike.
Vengeful is an alright Roaming partner with her stun and swap, and the damage boost is a nice bonus, but mostly she is useful with other heroes.

Honorable Mentions (They'll Work In a Pinch)

Easily Darkened

Even though you can move swiftly, you can be easily targeted and brutally murdered. Most any hero that can stun you will provide at the least a close call if not a death sentence. But there are certain heroes you must avoid for different reasons.
Avoid Rubick at all costs. He can use your Illuminate against you, or worse yet, steal Chakra from you and work it for his team. He himself is not terribly deadly, but his disable and spell steal will be your grave marker if you don't target/avoid him.
His massive damage and stun outputs will drop you in your grave faster than you can imagine. Best way to prepare in case he charges you, recall a friend to help you. Hopefully they themselves will have some type of disable to stun, because SB will be relentless towards you.
These two DPS's will most likely try to target you, which will slow you and deal DOT, both of which contradict Keeper's swift and powerful style.
His long-winded and damaging disables are a death sentence to you, unless he is working alone, and even then his ult can easily destroy you.

Any heroes that are proficient in disables, stuns, slows, and Damage Over Time are your worst enemy when going against you, and your best friend when working with you. Keep that in mind when fighting, these heroes were just particularly dangerous heroes that you should stay away from (Rubick especially).

Pros / Cons

Pros

Item Independent
Fast Base Speed
Great Teamworker
Excellent Support
Can Teleport People Across the Map
Possibly the Greatest Harasser and Lane Controller in the Game

Cons

Squishy
Usually Targeted in Teamfights
Stunned = Dead (Usually)
Weak in surprise attacks when alone