The higher the level is (e.g. max 150) he needs higher items like Giga Heart, Alpha Mosa Tooth etc. 3x you can wait the 5min and he will spawn the mentioned animal (except water animals). The 4th time, the altar will break and the Deadmare will probably be gone.

Spawn command : cheat sdf darkpegasus 0 150 1 (wild)

The altar will never ask for any tribute which is obtained from a sea creature as it spawns the creature if you don’t have the correct item and these cannot be spawned on land

It sucks to tame so just bring a pyromain and a giga and another giga and another and also a tek rifle

Ayntac posted a video on how to tame it

Requires random resources when summoning

First knock it out and then feed it the food it eats then it's yours