FWIW I am trying to be careful with healing because unlike Block you take it out of the fight. I don't want a situation where optimal play is to get one enemy left and spam heals, because some players will end up doing something I know isn't fun...
This means most heals have some restrictions like being exhaustible, dealing damage at the same time, or just being weak enough an enemy would outpace them.
Gwen's Rejuvenation spell heals 3 but has Decay so it goes 3, 2, 1, 0. But that's still 15-30% of her default maximum hp every fight (the same as the camp). It also has a short, double-green cast sequence that exists inside lots of other spells. So, as an example, if you were to pick up Rejuvenation + Leaf Cutter x Sling then on turn one, for three stones, you do a 15% heal and 6 damage because you cast them together...
Well, that's my thought process anyway!
(Also on Ceridwen Pact + Death Coil is broken and I'll probably change it, heh)