Hey I really like this mod! Theres alot of awesome mobs in this mod, I think it would be cool if you included some crafting recipes for the eggs for survival use. Maybe like 3 water buckets, 1 nether star, and 3 wither heads for a water wither. Keep up the good work with this mod! I also made my first mod showcase video for this mod so here it is!
make a pickaxe so you can break bedrock then if you can do so everytime you jump into the void you have a low chance to teleport to a dimension which is the void dimension and there you can fight the void wither
and the second idea is when you kill the ender dragon the portal appears and you throw a nether star into the portal to summon the The Wither Dragon