Manta Ray
What is your strategy for confronting the creature Manta Ray in Dungeons & Dragons?
More info on this D&D creature: Source 3
Being that they are nonviolent and have very low AC, hardly any HP. I would just do a basic attack on them. The only attack they have is to ram and that does 0-5 damage.
One tactic may be to try and grapple them. Then attack them while grappled, if they cannot use the ram ability they have no attack. Yet you can still attack them.