Fresh Hell.

At first, the products of the fusion were humanoid entities with many body parts. They grew bigger and gained more body parts as they absorbed more Tyrants and other amalgams. They quickly turned into a round ball of black flesh that couldn't walk or talk. 

The giant black ball of flesh had many grotesque limbs and wiggling tentacles growing out of it. The limbs were soon fusing into tentacles, which caused the number of black tentacles to increase. Soon it became more of tentacles than anything else. There was no trace of the Tyrants anymore apart from their black skin. 

Some of the tentacles entered the ground and took root. They elongated and entrenched themselves deep into the earth. They didn't stop growing at all.