1st is an AOE version of ''Chakra Magic'' with a big drain and gain cap. It's kind of boring and might need a tweak.
A way you can change this:
-To make it more interesting why not make allied heroes recover a % of the mana cost used to cast a spell
If you don't like that you can try :
-drains 10/15/20/25 mana per sec and for every 2 seconds in Seeping Magic it will deal 35 mana burn. So if a unit stays the hole 10 seconds it will loose
25x10 + 35x5 = 375 mana drain and also 175 dmg
your 2nd skill has no mana cost.. and again it regens your mana
you don't need your 3rd skill at all cuz you don't have spamable skills or retardedly big mana costs so like I said 3rd skill is useless.
4th skill isn't bad but seriously.. what's up with all the mana, baising 1 hero on 1 theme is a horrible idea since his skills can end up boring or compleatly useless.
There isn't all that big synergy between skills.. it's basically mana drain mana drain mana drain and for what ? Your hero does not use that much mana. You should try thinking of a secondary theme for your hero, this way you can easily find suitable skills to synergize with your mana spells. Also edit his BG, it's pretty good but the word ''magic'' is overused
Here's an idea, why not change 3rd skill into smth like this.
Zargreth releases strong waves of energy around him, dealing dmg from his current mp. The huge distortions causes his body to to loose phisical shape transforming him into raw energy which allows him to teleport short distances.
-deals X/X/X/X % of current mp
-your next step will cause you to teleport 200 units infront of you
-duration 3/4/5/6 seconds
-mana cost 100 to activate + X/X/X/X %per wave
-if you don't have enough mana the skill will stop
if your 2nd skill is like old soul steal it will synergise alot with this skill because it allow you easily to cath up to your enemy and also with the constant mana drain you'll be dealing a very reasonable amount of dmg.
I'm kinda tired to give you a % for the mp but here's a site where you can calculate easily %. http://asita.hit.bg/AM/percent.htm
If you don't understand it, paste it in google and press translate before etering the page (though it is quite self explanatory)