Origin
Doomprayer was said to be an enormous snake, whose coils wound around the Earth’s core. Mikas somehow managed to enslave this creature but it may have been a robot like many of Mikas’ servants.
When Mikas came into conflict with Iron Man, he made Doomprayer battle with him. However, it was ultimately defeated by Iron Man.
Creation
Doomprayer was created by Gerry Conway and George Tuska, with it’s first (And only) appearance being in Iron Man #43.