Well, as I mentioned, it would have been an option to trade off Cala and play Jaina on T3, so teching fire dart wasn’t necessarily a mistake.
I disagree that nothing synergizes with past. [Past]/Peace/Anarchy is considered a top-tier deck. That’s in large part due to the purple starter, though. Mox+boot camp is fantastic, and every single peace unit is a soldier, so Battle Suits gives a lot of mileage. Also you can play Flagstone Garrison without trashing Mox. I don’t see tremendous value in pairing past with Fire, though, because Jaina and Prynn kind of fill the same niche (targeted removal) in different ways. Another reasonable pairing for past is Discipline if you go for a TPoS strategy. Origin Story, Undo, and stewardess are all 3-cost cards that slow the game down, thus helping you build to a TPoS turn. Also Grave has combat abilities that Prynn sorely lacks. Blood seems like it would pair well with Fading stuff, since you get a lot more value out of it with haste (as you mentioned with Charge). Also, there’s nothing wrong with going double-purple or mono-purple.
In any case, I recommend re-thinking your codex. I’m not saying to change it, necessarily, but you should probably build it with some purpose in mind. I’m by no means an expert at this, in fact I’m a new player myself, but for instance I built my current codex with the main idea of abusing Plague Lab, and Disease Tech II generally. There’s some discussion about it here: What's your Favorite Deck? - #132 by payprplayn. Another thing to consider when you’re building a codex is answers. If you’ve got no way to get at heroes that aren’t patrolling, or deal with upgrades, or hit flyers before tech II, there are some decks you’re going to have serious problems beating. Again, I’m new at this myself, so it wouldn’t be a bad idea to solicit some help from a more experienced player. Alternatively, you can just go mono-colored, or try one of the consensus top-tier decks, which include (but may not be limited to): [Necro]/Blood/Truth, [Past]/Peace/Anarchy, [Demon]/Necro/Finesse, and [Anarchy]/Strength/Growth. I’m probably missing one there, but I know those are all extremely solid.