[Autumn]

I think Spirit Shell should make you able to have +2 additional spirits.

This makes Attune Grudge absurdly strong, I'd rather adjust that first before potentially granting them more spirit slots (which only further increases the RNG aspect of Attune Grudge), you can say all you want about Amalgama's gimmicks, most of them are pretty bad and don't warrant the health cost, but Attune Grudge is so powerful it might even be one of the strongest racials in perfect conditions, and that's mostly because spiriting has no downside so a good 50-70% of characters do it unabashedly, thats just a consequence of the current system.

Amalgama do not feel very good to play on a mechanical level and do need something else eventually, but I still continue playing mine cause of their IC mostly.