Whether its a sweet creature like Asylum Visitor or just a removal spell like Fiery Temper (and lets be honest, its gonna be Fiery Temper), Olivia does exactly what you want a 3-drop to do
You can tap, put a few counters on a key creature you have to kill
That means we have to calculate the odds of drawing at least one ramp spell in our first 10 cards (including opening hand)
One of the better options for a self-discard deck in blue and red is Rielle, the Everwise
Her first ability is a wild one, Nontoken artifacts you control are lands in addition to their other types. This protects your artifacts from many of the most common removal spells in Commander, like Vandalblast, which can only target nonland permanents
At the very least, trying to find it is more fun, and the practice helps the next time it comes to build a new deck.