Trained on 438 gelbooru images for 5840 steps. I made this for a request, and it worked out pretty well.

You shouldn't need a hard trigger, but it doesn't hurt to to add:

Yellow Sclera, Sharp Teeth, Blue Skin, Blue Body, Red Hair, Ponytail, Eyepatch

Casual outfit:

Black Tank Top, Jeans

Undying:

Undyne the Undying, Armor, Spear, Weapon, Polearm

Deltarune:

Deltarune, Policewoman, Police Uniform, (Eyepatch in negative)

Has a couple bugs but nothing inpainting can't fix.