Hand of Greed

Hand of Greed is perhaps my favorite.  It shows 20 HP damage below, though as a note its upgraded version does 25 HP and provides 25 Gold.

Any non-minion target is viable.  The Hand of Greed is repeatable, unlike the Feed card.

Notes

• Repeatable. 

Event Synergy

• Arena event.  This event allows you to fight and potentially consume x5 non-minion creatures.

Monster Synergy

• Best used in multi-monster encounters, where you can take advantage of consuming more than one per encounter.
• Any monster group of three (3) - Several of these exist from slimes to cultists, byrds, etc. 
• Darklings.  Also in a group of three.  Note, however, it doesn't look like you can take advantage of their return back to life to consume them multiple times.
• Gremlin Gang.  Usually four of them.  This can provide 80 to 100 gold in an encounter.
• Slimes.  When slimes divide, they are noted with an (M) next to their name.  These are not valid targets for the Hand of Greed.