Weird cards to consider: Creatures, Artifacts, and Enchantments.

These options do not play as nicely with Pyromancer Ascension.  They don't get copied, or charge it up.  However, they do typically go through a different kind of removal, and game 2, your opponent might not have any of that kind of removal left.  This is most plausable against decks that do not have Red, or Green (who can often block these creatures, or who are playing bigger or the same but faster versions of what you would be trying to do.  Black also tends to have Gatekeeper, which is a great answer to all of these options.

On the plus side, they tend to dodge Duress, Celestial Purge, Revoke Existance, Luminarch Ascension, Negate, and a few other answers you might see.

Creatures:

Very aggressive.  Often bad with countermagic.  Often killed by cards they leave in anyway.  (Bolt, Gatekeeper), or just blocked and killed by Lotus Cobra, Oracle, Kor Firewalker, etc.  Drops on T2 on the play, avoiding Mana Leak, often the only answer control decks have to the creature sideboard plan.

Good against White/Blue/Black/Red, unless they have 1 power blockers (Trinket mage, Gatekeeper).  Bad against green (they will have the blocker).  Probably reasonable against vampire aggro (Bloodghast killer) if they didn't have Gatekeeper.

Pyro Ascension 5-8, this guy is pretty mana-intensive, but neither red (Celestial  Purge), nor an enchantment.  He also dodges Ratchet bomb, or forces it to go to 3 instead of the mono-2 you present with Kiln Fiend + PA.

Flys right over the titans. Top card viewing could be very useful for a deck with Treasure Hunt, Scalding Tarn, etc.  Most likely counter to this is Mana Leak, and getting to 9 mana to prevent that is often troublesome.  Comes down after all the counter fights, so perhaps a good answer.

Not a terrible answer to Frost Titan, but requires 8 mana for full effectiveness.  Beats down pretty hard.  Among the more pro-active options available.

Beats down amazingly hard.  Ends the game in 1-2 turns.

Better against Gatekeeper than other options, and blocks KFW, but Revoke gets him pretty hard.

Blocks creatures pretty well.  Great answer to Kor Firewalker, or Bloodghast.  Acceptable answer to the landfall guys, or other aggro red threats.  Not great vs. Argentum Armor, Frost Titan, Wurmcoil, Gatekeeper.

6 mana full-answer to Frost Titan.  (About as cheap as you can get in Red-Blue).  Very reactive, which is not terrifically good.  Bad as a 4-5 mana answer to Frost Titan, because they'll just tap it on the way in, and you lose.  Not awesome vs Eldrazi (You get the copy effect on ETB, and the Eldrazi effect on cast, so you don't get it).  Probably too reactive to see play without other threats to back it up.
But hey, who doesn't like a card with 9(!) rules clarifications on Gatherer...

Artifacts:

Pretty good vs. aggro, pretty good vs. Ratchet Bomb, pretty good vs. tokens.  Requires a slow play of the Ascension, but slow playing PA is often the best idea anyway in these matchups.  (Playing it early is only good vs countermagic)
Planeswalkers:

Beats J:TMS to the punch.  Draws cards.  Not really a wincon.

Out of my price range and CC range at this time.  He's expensive for a reason though.

Powerful, but probably bad against Ramp.  Might be good against control if it can land and survive through the hate they already have.  Worth mentioning most likely.

I'm open for more options here.  Good spells here will be quite a bit harder to find than good instants or sorceries.