At a baseline, Afterlife Insurance naturally helps solve this, letting you replace whatever you sacrifice for more Casualty fuel
Minsc, Beloved Ranger Theres a lot of steep competition when it comes to three-mana creatures in Cube and Naya is generally not a very inviting combination of colors, however Minsc is worth discussing because if youve spent much time looking at options for Naya cards the options just arent very good
Dark Confidant Although its fallen from favor, Dark Confidant is a premier 2-drop, 2-power creature in black thanks to the ability to draw an extra card on your turns
Umori is a case where doing so is the clear best option, letting you easily access its overstatted, cost-reducing goodness without nerfing your deck with a lack of variety in card types
Where the real power lies, though, is with Sphinxs activated ability
Instead, I studiously avoided playing any spell that might allow him to cast a counterspell, simply to prevent him from activating the Rod