Soulmender > Alseid of Life's Bounty: This was always an intended swap as soon as I got my hands on an Alseid. My LGS had a fun event during their AFR prerelease where you could satisfy "quests" during your matches and win promo packs they had built up. I ended up pulling an Alseid from a THB promo back! I'm not sure lifegain needs much help but I'm open to testing Soulmender more in the future; could be some interesting play patterns.

Grim Physician > Shambling Ghast: First AFR swap, and a strict upgrade. Right now I'm toying with black having a theme of "risk" both with cards like Infectious host that are risky for black to play, but also creatures that generate value on death. The ramp and fixing from a treasure could be helpful too if black continues to be a pip-dense color. If Shambling Ghast turns out to be too powerful, it can always be downgraded again.