Magic Mirror would be too overpowered if it could do both. It only works against abilites, meaning, I assume, any non-physical attack such as stuns, DoTs, and elemental strikes. If you have any experiences of a physical attack being reflected, though, I'd be interested in hearing about it. 

I find Magic Mirror worse than Silent Pace because it can activate at any time in the battle. Silent Pace is hit-or-miss; if you countermove it on the first turn, you won't have to worry about it anymore. With enough fights and a bit of luck, you can eventually defeat it. 

I think the Tundra monsters' actual genes are not correlated to the level they're found on. I've run into monsters with special abilities on the first or second level. My theory is the Tundra level just gives a stat boost to all the monsters on it, though the abilites definitely make them worse.

Another tip I can think of as helpful would be to have the number of hitpoints ("health") as high as possible. Until now I was under the impression it depends on both strength and constitution, since in the Characteristics description table it says both are responsible for defence, but a very simple check has made me think it is not the case. For now, the only solution to this, that I know about, would be thick skin.