Gift of Yeenoghu (passive of the blue mace found on a gnoll possessed by a tadpole) is broken: any harmful effect, be it an attack or a spell, triggers the healing effect of the weapon.

Halsin is broken: he can't cast his spells and can only use his melee.
Also, when the animal form of a druid dies (so here: when the bear dies), the druid doesn't die as of D&D 5E ruleset. They instead lose their form and any leftover damage goes over to their human form.

Another thing: I just summoned the frog (wizard animal companion), and used its jump ability. The frog has 1 hit point, and died upon landing after jumping to its max range. So, yeah.