Namely Elspeth, Sun's Nemesis and Ashiok, Nightmare Muse
Once it's at five mana, it can start dropping huge threats like Stormbreath Dragon onto the tableand at six mana, here comes Dromoka and Harbinger of the Hunt
Hollow One cares specifically about the word "discard." Wraith's two-life cost makes it a tough sell in other decks thanks to the format's aggro decks, especially Burn
On the other hand, theyll try to play these cards in a spot where they have protection for it as well in the form of Rattlechains or a counterspell, so the key is to ignore their small, irrelevant creatures and then engage in a counter-war over their key cards as likely you will need two, or even three, removal spells to get through their protection
Sacrifice after III.) I, II Tap target creature an opponent controls