Vengeful spirit is a hero that is viable throughout all stages of the game. She has a great lvl 1 stun and her passive ability allows your cores to do a lot more extra damage. Her second skill, wave of terror, weakens up the enemy and allows you to gain vision for a swap. Focus your swap on their squishy damagedealers or just a meaty target that is cut off from the herd. Dont forget you can also use it to save your allies!