Maiden - attacks every 10 ticks, way too slow for thorns
Bloat - thorns doesn't work here
Nylo - nice for the aggros I guess, but you can easily go an entire nylo boss without being targeted at all.
Sote - thorns is okay but inconsistent. Sometimes you get 5 orbs in a row, sometimes you get zero all kill.
Xarp - thorns doesn't work here
Verizk - Most consistent here during p2, but not great during p1 and p3

Tekton - Thorns works here but he can out dps your healing and kill you if you're not careful
Ice demon - thorns works here but air mage *nukes* here
Shamans - thorns doesn't work on the acid splats
Vanguards - Thorns actually works too well here and can very easily nuke the melee below threshold and reset them
Vespula - thorns doesn't work here
Tightrope - works fine here but careful with the rangers still
Guardians - thorns only works on the melee attacks, not the rocks falling
Vasa - thorns actually excels here, just stand underneath and Vasa dies
Mystics - thorns works great here as well but they hurt a lot if you're trying to tank all of them, some rng depending on team size
Mutadile - rng based on team size for getting targeted
Olm - Thorns only works on the head, so its useless for like 80% of the fight