
Darksol the Painbringer |

Hello, for the protector tree, is it only the ally adjacent ?
Or the tree interposes also for the caster of this spell ?
Is it possible to improve Hit Points without heightened the spell ?
Thanks for your future answer.
By RAW, yes. Only an ally can benefit from this spell, and not one's self. By RAI, I would disagree with that sentiment simply because there is no logical reasoning behind casting the spell to help protect yourself because, other than arbitrary limitations, there's no reason the tree can't interpose a blow dealt on you. I would personally allow the tree to protect the spellcaster, especially since a cantrip like Shield already exists and has a similar function while also increasing AC and taking less actions to do so. So, it's possible for it to do so, but that's GM purview, so YMMV.
As for increasing hit points without heightening, I don't think so. There are spells which provide healing (but don't improve maximum HP), and spells which give temporary HP, but both of those only function on creatures, which I would not argue is a valid target for this spell effect; at least, not until its duration expires and it proceeds to be its own, living being, and not an effect sustained by a spell. After all, once the spell ends, if it still remains, it ceases to protect others, and it states to be as any other tree in the world.
IMO, it's not a bad proactive use of spell slots, especially in the higher levels to help with damage prevention with your lower slots, as I imagine there aren't too many other good lower level slots to use spells on as a Primal spellcaster. Maybe Longstrider and Haste?