The -3 isn't flashy, but you can't complain about removal (that can be used the turn it enters) tacked onto an already stacked card
She also lets you draw a card at the end of every players turn if any player loses 4 or more Life that turn, which given the multiplayer nature of Commander, could reward you if others are playing well (or poorly)
However, if Everflowing Chalice has no charge counters on it, activating its last ability won't produce any mana
It looks like some of these double exposure cards have a ghoulish shimmer to them
However, these split cards are permanents that enter the battlefield when they resolve, and the second room can be opened at a later time by paying its mana cost
Brimaz, Blight of Oreskos looks like it fits in the same category, though its more of a self-contained engine in an artifact-heavy deck than a full-on Phyrexian commander