They can be killed if you have the sword, if you don’t than you should try to avoid them (or use the DreamHit mechanic)
I already got the sword ingame, and I hit the rat for once. The rat is still alive and kills. And I will just delete this comment because they aren't truly invincible in-game. As you said? Doesn't sound right.
it needs 2/3 hit to be killed :D
