Warrior's Pact is useful if you find Pactmaker late and it's no longer feasible to build up appreciable results with Body Pact. It's expensive, but if you need to push your HP over the edge it's a life-saver. It works very well with Taurog, Dracul, and Tikki Tooki which all generate sufficient piety as you clean up your popcorn to fuel this pact.
For flames, I want to be clear that it does work for pure fireball characters and that bottom tier is not necessarily useless, but a -50% attack bonus penalty is nasty. Presuming you have normal base attack (5 per level) with no other boosts, this is -2.5 attack damage per level for +1 fireball damage per level. Put bluntly, you need to make three fireball attacks for everyone one physical attack for this to pay off. Definitely doable, but I find it's largely only worthwhile for Assassins and Wizards or against bosses like Bleaty that you just can't touch anyways.
As I mentioned I'm not rating Mystic Balance because it was introduced in the last update and is blatantly broken. It's top-tier material and everyone here knows it, but it's going to be gone or at very least reworked next version.