Dusk // Dawn is tailor-made for this deck since you wont lose any creatures (aside from your commander), and ditto for Slaughter the Strong
Plus, the modern take on this effect, Xanathar, Guild Kingpin, is even MORE expensive to cast (probably thanks to color fixing and the ability to see more cards)
Prosper, Tome-Bound Treasure and card-draw Tiefling warlock Prosper, Tome-Bound is a four-mana black and red 1/4 with Deathtouch that does a lot all on its own, but none of that is really combat-based
Crossway Troublemakers is a little bit expensive and you have lots of card draw going on
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