WindRunner7

I don't think regular spawn eggs work with deferred register. The item registration happens before entities so when registering the spawn egg the entity registry object is no present. Try taking out the spawn egg code and it should work fine. Here is an additional thread on registering entities with deferred register. It also goes over what needs to be done to make spawn eggs work. It is for 1.15.1 but should work pretty well with 1.16.5 as well.

You will need to override the travel method. There is a good example of this in the AbstractHorseEntity class. public void travel(Vector3d travelVector) { if (this.isAlive()) { if (this.isBeingRidden() && this.canBeSteered() && this.isHorseSaddled()) { LivingEntity livingentity = (LivingEntity)this.getControllingPassenger(); this.rotationYaw = livingentity.rotationYaw; this.prevRotationYaw = this.rotationYaw; this.rotationPitch = livingentity.rotationPitch * 0.5F; this.setRotation(this.rotationYaw, t

I believe you are missing the rotate/mirror functions. I believe that these are called when the structure is generated and is being rotated. I got these from the StairsBlock.java class. public BlockState rotate(BlockState state, Rotation rot) { return state.with(FACING, rot.rotate(state.get(FACING))); } public BlockState mirror(BlockState state, Mirror mirrorIn) { Direction direction = state.get(FACING); StairsShape stairsshape = state.get(SHAPE); switch(mirrorIn) { case LEFT_RIGHT: if (direction.getAxis() == Direction.Axis.Z) {

Is there any more info you can give on what you are trying to do? Also, do you have a repo? Being able to see your code would be helpful. At a minimum can you post your custom block code? Someone can correct me if I am wrong but I don't believe there is any way to generate structures without *.nbt data. Why are the *.nbt files an issue?