People often complain about Fire minions, as well as others, but I hear mostly fire. Anyways. You can level up your wizard, your pet, why not your MINION? They are always Rank 1 even if you use 4 pips on it. I think you should be able to adjust it's deck and strategy. As it levels up (by fighting with you?) It gains new cards, as it gets better it costs more pips. I am not saying things like 8 pips for minion with 3000 health, knows earthquake, orothrus, minotaur, pierce, cleanse ward. No no no that be WAY over powered even for 8 pips. Just it gets an attack boast or defense boast. Notice how minions have no weakness or boast advantage? Not really is? Ex. Cyclops minion 4 pips, ranks up to Cyclops 5 pips. 100-200 extra health. Each card the 4 pip knew, the 5 pip knows 1 rank better. Like from sunbird to meteors, or cyclops to hummongofrog.
If you want to play with a minion who can get better, play death.....if you change the current system, death's minionswould either loose the special nature of calling out different types, or become really, really mean.
By the way, do you really play with minions? I notice few do play with them after a few levels of gaining them.