Warpiglet
Adventurer
Remember though these MC are carefully chosen and designed to be better on balance then getting those things through a single class. The Optimization forum is full of the analysis. That's why its done, and having something well thought out and planned should be encouraged and worked out with the DM first to smooth over any troubles.
Some--many of them? are but not all of them. All but a few combinations are less powerful than a single class character.
Our assumptions shape a great deal. What if someone just likes to play a fighter/magic-user? Ahem, wizard? Is that terrible too? The fear of someone gaming the system can ruin it for the rest of us if we allow it to do so.