I just killed the T-Rex in the stupidest way possible. The short version is the cow is OP.

I have a cow with a health-on-hit effect and I got on it and charged the T-Rex, and just air-juggled the thing from one end of the arena to the other, then repeated the other way until it died. Every once in a while the T-Rex would land a pretty substantial hit, but due to just how many times the cow was hitting him back it'd heal pretty quick.

it turned what was supposed to be a rather tough boss fight into a Monty Python sketch.