Here's how I got Flawless Victory on the cheap, if anyone else is wondering (FYI my pet has the 55 boost, that's it):
1: Scroll of Knowledge + Green Frost Cannon + Static Cling
2: Leaf Shield + Green Frost Cannon +/- Static Cling
3: Repeat #2 until opponent is frozen BUT NOT DEFEATED (be careful, the frost cannon does 3 icons per round)
4: Scroll of Knowledge + Jade Elixir + Static Cling
The frost cannon keeps the opponent from attacking that final round, so you can chug that jade elixir to full health and knock him out with the scroll (or whatever your best weapon is).
Jade Elixir is a one-use item and costs 15k (there are quite a few on the shop wizard right now); I don't remember how much the green frost cannon costs - I think I won mine as a BD prize in the ice-themed arena, actually. It's a pretty basic item.
Haha, you lucked out and got the glitch, I see! For most of us you can only get the achievement with this wave's opponents.