Does Curse of Conformity stop etb abilities from happening? Let’s suppose I cast a Harmonic Sliver and then try to target Curse of Conformity my opponent puts on me, does that prevent the etb ability from triggering and be put on the stack?
Well, you really have two questions here. First, Curse does not remove abilities. So Harmonic Sliver would still have its ability granting Slivers the ability to destroy an artifact or enchantment on ETB. However, you are specifically using a card that Curse *does* stop but only because it removes creature types. Since your Harmonic Sliver is no longer a Sliver, it will not grant its ability to itself so it can't trigger.
If you used something like Reclamation Sage it would work just fine.
If you used something like Reclamation Sage it would work just fine.