Also, another question- why is it that sometimes my fully charged illuminate will completely desolate an entire creepwave some times, but leave some of the melee creeps with a fraction of health at other times? This is like two identical circumstances- Is the creeps' magic resistance variable or something?
Lane creeps actually gain stats ove the course of the game, getting stronger even if you don't destroy a barracks. So the creeps you see 30 minutes in have more health than those at minute 0.