I'm pondering alternate rewards for urkis, feedback sounds fun but it's already an escort reward. And giving a prodigy feels too much
Give the player a shroombuddy instead of fungus/talent access. Time hound style entity (though probably just a single one out at a time) that costs either nothing or a bit of EQ to sustain, and automatically respawns after death (fungus tree procs and/or infusion use making it faster). Pop on a few interesting unique talents -- reactive poisonous spores (percentile proc when hit, or put on a CD when it triggers), passive auto-spread a randomizing moss, improve fungus and/or infusions in some odd way when it's alive,* some sort of movement/rush ability (and/or probably link its base movement to either your base or current, so it won't screw around halfway across the level because you've got wanderer's rest on or somethin'), add a temporal hound style takes-few-turns-to-die (something like a shorter duration effect compared to the hounds, but let it extend a bit if you use infusions/fungus talent effects while it's dying) thing so you always
get some value out of it, no one turn deletion nonsense. Some kind of taunt (make it single target and damaging/debuffing, to differentiate from the current mostly-AoE-and-no-other-effect taunts) to make sure things pay attention to it. Let it eventually pick up some overt AM effects (spell feedback/mana clash/eyal's wrath, choose one**) in the 40-50 level range. Don't give it much straight-up offensive ability (bump damage, etc.), but do have enough debuff/annoyance/utility/indirect damage to make it worth calling a reward.
Then you'd have something neat, considerably more interesting than some random generic tree, and useful to just about anyone (everyone loves something else drawing fire, doubly so if it can't die in one turn, and especially
when it's cheerfully screwing with the enemy in the process), that still slots in with fungus thematically but isn't actually the tree. Could even take the fungus reward away entirely, leave it to make the current fungus users' access more unique while still having the reward specificly synergize with them.
Give zigur a murderhobo mushroom mascot, basically.
* Some sort of echo effect, where whenever something appropriate activates the shroombuddy does something. Spits out a tiny will o' wisp style suicide minishroom, I'unno.
** Alternately let it pick up unique poisonous spore and moss effects, that either add in antimagic themed options or add an antimagic effect of some sort of the current ones. It could even share the effect (when it's alive) if you happen to be an oozemancer (or have vile poisons, perhaps) yourself.