To avoid impulsive decisions, set clear goals before trading
Summon: Magus Sisters Summon: Magus Sisters give you a great benefit in most cases, and randomly it won't work the way you want, but at least in each mode you get to choose the targets
Liberty Prime is absolutely a beater, but with no way to protect itself, you're mostly just swinging with an 8/8 for five mana that might also cause you to sacrifice it at the end of the turn
She can make a 3/3 trampler for free every turn and rock the block while doing so
Well, madness, jump-start, and flashback come to mind
There are a few fringe scenarios where you might want to intentionally cast a second legend after attacking with the first copy, just in case you need the blocker