Why does this make me think of Hearthstone...
Anyways, this is a very nice finisher in-element. Especially when used with Mitosis. I guess combination with Chimera would just further cement this as a finisher if you don't want to leave it up to chance.
And I suppose the shield ignore effect would stack with Shard of Freedom?
Because once in an arena run, the opponent was standing at 8 HP left with a giant and a Venture Co. Merc on the field. I had 25 HP. It was turn 7 I think and I would win next turn. But just for insurance, I had a goldshire footman on the field (don't ask). So he plays Druid of the claw in charge form, then innervate + savage roar, hits off the footman with his hero and then beats me down with exact damage...
And then, this idea was born!

(I should stop ripping off Hearthstone for cards).
SoFree should be multiplicative with this IMO. Multiple Rages would also be multiplicative.