Some ideas here:
Zarthas (worst name I've ever thought off)
History:
Zarthas aims to kill Arthas to forever remove the great title Lich King from Arthas. His goal of becoming the Lich King, makes him corrupted and acts like an evil hero. Even as an evil hero, there are some yet few people left that trusts him and loved him.
Zarthas is actually half bad and good.
Crysta - a legendary sword that has the blood of the ice princess named Crysta. Crysta is believed to be strong that she can cast ice spells far powerful than normal ice element based power. This sword is wielded by the warrior Zarthas as his main weapon.
Stats:
Strength - 22
Agility - 15
Intelligence - 17
Spells:
*Wrath of Crysta
-Zarthas concentrates all the ice powers and particles at the tip of his sword, Crysta. After 3 seconds, unleashes it and deals x damage and freezing enemies at place for x seconds in a line.
*Crysta's Blessing
-Zarthas uses his sword, Crysta to cast upon the target an ice orb circling the target and slowing enemies near it for x%. Blessing lasts for 10 seconds.
-Slow stacks up to x%
*Battle Stance - Crysta's Soul
-Every hit that Zarthas makes, gives him bonus x% attack speed and at the other hand, hitted enemies' movement speed suffers and decreases it by x%.
-bonus attack speed and movement speed deduction stacks both up to x%
*Finale - Storm
-Zarthas concentrates his energy and casts an ice explosion at the targeted unit, dealing x damage to targeted unit and units affected in AOE and after that, bounces to nearby random enemies but deals x% less damage until it reaches its peak of 0%.
-Additionally, after casting this strong spell, reduces Zarthas's damage by 50% for 5 seconds.