If you have multiples of Dragoons Lance and Red Mages Rapier (by far the most powerful of the equipment cards in terms of pressuring life totals early) and copies of Suplex or Slash of Light to force through those attacks, you can go all-in with finishers like Unexpected Request and Zidane, Tantalus Thief to steal games before the opponent gets going
Many of the Guilds of Ravnica and Ravnica Allegiance split cards fit the bill because they provide an easy-to-cast front half with oftentimes powerful back halves
Unlike tying card drawing to creatures attacking (which happens often enough) or taxing (which mechanically has a huge build-upon base), equalizing card draw is a catch-up effect
This one is semi-coherent
A two mana 2/1 with Lifelink is usually playable anyway, and this will often be a 3/2 or larger on your turn
Mana Ramp Lastly, we have the expected mana ramp options for Boros, plus Patriars Seal, which can untap Rainbow in a pinch