Enchantments There are a variety of good permanents you can drop that draw you cards on damage like Virtue of Courage, damage doublers like Dictate of the Twin Gods, damage triplers like Fiery Emancipation, as well as card that add bits of damage (and the ever key triggers for these cards in this section) like Mechanized Warfare and Roiling Vortex
Regrowth might be cheaper, but Eternal Witness feels far more impactful due to the ease with which you can flicker it
One card serving as an accelerant, discard outlet, and card draw is remarkably efficient, even at 4 mana
Conduit of Emrakul Creature Eldrazi Werewolf 5/4 Whenever Conduit of Emrakul attacks, add CC to your mana pool at the beginning of your next main phase this turn
I love Planeswalkers that can be cast and can immediately create a creature to protect itself
Its Black Lotus with upside in decks with dredge that want to fill their graveyard