There's an exploit for the witch Ir Yût. Get on top of the map when you load the checkpoint, jump down into the room above the crystal and when everyone else kills wizards and shrieker you can solo the witch while taking minimal damage. The rest of the fireteam can focus on wiping the knights and acolytes to clear the checkpoint. When you liturgy starts, she stops moving and does her little rain dance which makes this exploit cake. Ps. Unless there is a prior topic involving this cheese/exploit I take pride in finding this out for myself, world 1st?