Vasal of the Seal vs Preserver

Overall comparison

HERO	Fraction	Element	Type	Rarity	Aura
Vasal of the Seal	Demonspawn	Force	HP	Legendary	HP 33% Place: All battles
Preserver	Banner Lords	Force	Defence	Rare	HP 17% Place: All battles

Stats comparison

HERO	LVL	STARS	HP	ATK	DEF	SPD	C.RATE	C.DMG	RESIST	ACC
Vasal of the Seal	60	6	21315	870	1288	98	15	50	40	20
Preserver	60	6	16350 -4965	771 -99	1167 -121	102 +4	15	50	40	0 -20

Skills comparison

Vasal of the Seal	Abyssal Seal Formula: 0.25*HP Attacks 1 enemy. Places a [HP Burn] debuff on the target for 2 turns if they are under a [True Fear] debuff or a [Decrease ATK] debuff. Also places a [Shield] buff on this Champion for 2 turns equal to 10% of their MAX HP. Shield HP Burn	Infernal Darkness Formula: 0.27*HP Attacks all enemies. Has a 75% chance of placing a [True Fear] debuff and a 50% [Decrease ATK] debuff for 2 turns. Cooldown: 5 True Fear Decrease ATK 50%	Daemon Possession Balances the HP of all allies. The HP levels of all allies will be brought up to the level of the ally with the highest HP. After balancing HP, grants an Extra Turn. Cooldown: 6	Legion of Doom [P] Formula: -0.2DMG_MUL Formula: 0.2DMG_MUL Receives 20% less damage from Champions from the Banner Lord, High Elf, and Sacred Order Factions. If there are 2 or more Demonspawn Champions on the team alongside this Champion, increases the C. DMG of all Demonspawn Champions on the team by 20%. [C. DMG increase only works when this Champion is alive.]
Preserver	Exhausting Assault Formula: 5.5*ATK Attacks 1 enemy 2 times. Has a 15% chance of placing a 30% [Decrease SPD] debuff for 2 turns. Decrease SPD 30%	Recuperate Places a 7.5% [Continuous Heal] buff and a [Shield] buff on this Champion for 2 turns. The value of the [Shield] is proportional to this Champion's MAX HP. Cooldown: 4 Shield Continuous Heal 7.5%	Ice Blow Formula: 6.7*ATK Attacks 1 enemy. Has a 75% chance of placing a [Freeze] debuff for 1 turn. Cooldown: 5 Freeze	-