Talking about this whole "Arcane Blocking" ability, I know it seems OP because it is an instahit, but what it does is basically "locking" (or at least making them extremely lengthy to cast and make you very tired) your most powerful spells. Basically anything that requires too much mana. You are receiving less mana from the Arcane Network than you would normally.

All other spells and abilities that doesn't have a high mana consumption works normally.