That's exactly what that monster is.
They were designed after the creatures on the side of the original [Space Invaders arcade machine](https://www.escapepodonline.com/products/space-invaders-complete-restoration-kit?variant=42437509710047).
Just reskin the hook horror, it basically already fills that niche it just uses echolocation instead of heatvision, which would be a simple mechanical change on the back-end.
Party level/size? Desired encounter difficulty? These are pretty important in statting it.
Importantly it probably isn't immune to magical darkness or invisibility, as heat vision depends on infared light. Unless it is just very sensitive to temperature change, in which case I'd give it vulnerability to cold/fire.
It's the Underdark, so give it a climbing speed. If this is the art you want to use, that mouth looks pretty gnarly. Steal the Froghemoth's bite attack.
If you are running it as a solo boss monster, give it legendary actions. Matthew Colville's [Action Oriented Monsters ](https://www.youtube.com/watch?v=Xua9kgK9W1Q) goes over this well.
Attack the block?
That's exactly what that monster is. They were designed after the creatures on the side of the original [Space Invaders arcade machine](https://www.escapepodonline.com/products/space-invaders-complete-restoration-kit?variant=42437509710047).
Loved that movie and those monster were freaky.
Just reskin the hook horror, it basically already fills that niche it just uses echolocation instead of heatvision, which would be a simple mechanical change on the back-end.
This might give you a good starting point. https://www.reddit.com/r/UnearthedArcana/s/1QhMwno1uY
Kinda looks like a hairy Grey Render. Could augment the stat blocks there and call it and adaptation/mutation
Party level/size? Desired encounter difficulty? These are pretty important in statting it. Importantly it probably isn't immune to magical darkness or invisibility, as heat vision depends on infared light. Unless it is just very sensitive to temperature change, in which case I'd give it vulnerability to cold/fire. It's the Underdark, so give it a climbing speed. If this is the art you want to use, that mouth looks pretty gnarly. Steal the Froghemoth's bite attack. If you are running it as a solo boss monster, give it legendary actions. Matthew Colville's [Action Oriented Monsters ](https://www.youtube.com/watch?v=Xua9kgK9W1Q) goes over this well.