Making your mana work with only a ticket or so is a good place to start, and theres a lot of pre-existing solutions: Two- and Three-colour mana bases (sans green) To start with, a surprising number of top-shelf mana fixers are 1-3cT
This is good in an aggressive deck, and I think black/red will be especially interested in this, just make sure youre likely to maximize both cards as much as possible
That creates a larger deck stack, particularly when combined with inner sleeves, but the added thickness is part of their appeal for collectors carrying high-value cards
It's easy to see why, since it brings the Power Nine into your deck, and allows you to scry one on each attack
Specialty hobby shops and local game stores are reliable sources since they regularly stock singles, older sets, and sometimes even showcase rare cards behind the counter
As a treachery card with Vengeance X completes its resolution, place it in the victory display instead of in the discard pile