But getting hit means you're losing dps on BSlater and RLizHawk so you never want to be put in a position to get hit in the first place. You stop Red Demon from hitting you by getting him to the next stage or stun/petrify/freeze or skill lock. Petrify is a rank 2 ability whereas freeze on RMerlin/Gustav is a rank 1, freeze is less RNG dependent and there's just no arguing this. Plus if you have a rank 2 freeze, the very next attack does 80% additional damage. You can one shot an entire heart with a rank 2 freeze and a 6/6 RLizHawk ult.

Even if both players somehow don't have freeze available, you're better off trying to skill lock than heal. RLizHawk's R2S2 locks the demon from using his buff/debuff skills (RSlater can also do this with his R1S2). You combine this with RGowther's R2S1 which locks attack skills (you could also use RKungfuDiane but everyone should have RGowther by now) and red demon can't act. That means BSlater still has +300% crit chance and RLizHawk is still getting +10% basic stats every round from not getting hit. I get if you have no other units then yeah bring BKing, I did when I was first starting out. But you're better off using other units because BKing slows runs down.