Aether Command
Instant
Conversion — As an additional cost to cast this spell, you may discard a card from your hand. If you do, this spell costs {2} less to cast.
Gain control of target creature spell. (It enters the battlefield under your control.)
"Esha stokes the heart's flames until you see nothing but blood and can no longer tell friend from foe."
— Osthia, Shaiel Benevolent
This is to be a flagpost uncommon for limited (RU/RUg Tempo), so the latter is acceptable to me: flagpost uncommons are often pushing the bounds between uncommon and rare.
The former, however, is more the main issue for me. It's a result of redesigning the card multiple times, which eventually washed the red out of it.
The design isn't actually set yet; I wanted to see the full card while I finished thinking it out. As much as I love my elegant simplicity, this card needs something else.