Also, somethign else to keep in mind, you need to get the prism on FIRST because stacking spells come off in REVERSE ORDER of how they were applied. SOME spells don't matter, but most do. So, let's say you do a fire prism, fire trap and elemental trap. When you hit your damage, it'll get stacked by doing elemental trap first, fire trap second, and fire prism last.
If you cast fire trap, fire prism, elemental trap, you'll get damage modifiers for elemental trap and fire prism ONLY, because once you've prismed it, it's no longer a fire spell. I learned that the hard way!
Now, I said some spells dont matter the order, the death school spell (which can't be trained outside of death school, but you can find treasure cards) Hex is like this; it will add 20% damage to ANY school's spell, regardless of which order it was cast in.
Does that give you a better picture of how stacking works?
My pyromancer was able to solo most of the game up until Avalon, and that was while not even using blades/traps till.... probably after grizzleheim! Yeah, I know, it was a CHORE lol I had nobody to teach me these things and I didn't discover these boards or other fan sites until later. Make sure you kill the minion first. With rare exception, killing the minion first makes it MUCH easier on you. I've fought battles where the cards just came up right, against the right boss, that I could take it out on the first hit (with stacking damage of course), but that's not the norm.