This card seems OP to me. I'm also wondering how this could ruin other cards. I mean, with this card, many people will replace their other creatures + adrenaline combos (why bother pulling off 2 card combos if they have this card?). I'd say there needs to be some kind of limitations like maybe this card is not targettable.
You might then be unhappy that this card would not be as strong. Well, to balance that, I'd say change that light skill completely. Here's my suggestion:

Iaigiri: This card's attack power is doubled for 1 turn.
Iaigiri is a symbolic ultimate sword technique for Samurais, so it's more appropriate than healing. You could even change the element from light to something more appropriate too.
I know you didn't do it, but I like the artwork.