Being able to not just reanimate creatures but actually play any kind of permanent from your graveyard each turn lessens the cost of sacrifice mechanics while bolstering your threats from single-instance removal
Then you spend to forage (exiling three cards from your graveyard or sacrificing a Food token) to toss a +1/+1 counter on all of your Squirrels
If I had a wizard commander in these colors, I might prefer Flame of Anor in quite a few situations
Abyssal Harvester is worth noting as another demon to pair with Unholy Annex, but I think not having decent stats or a powerful enter the battlefield ability make it just not good enough
Otherwise, there are fantastic favorites like Thran Dynamo, Bubbling Muck, and Elvish Piper from Urza's Destiny
Unearth only as a sorcery.) If you activate a card's unearth ability but that card is removed from your graveyard before the ability resolves, that unearth ability will do nothing as it resolves