Anki can attack directly using its effect, but it will only deal half of his attack. This can be "negated" by using Forbidden Chalice during damage step so that it will deal 3200 damage directly. But it is best not to battle a monster with Anki with Forbidden Chalice because he will not get his search effect.
I don't get why this card is that good... Ultimate Providence / Divine Wrath need a discard, but they can replace Forbidden Chalice, especially because the targeted monster is destroyed! In a 20 card deck, I don't see any need of this one.