Living is mass sac of creatures for all players and then mass reanimation of the creatures that were in graveyards before the ones that were saced
The negative of both abilities is that it can only eat Swamps and Islands, making some of the other dual lands less than ideal
The cost of discarding a card can also be a great way to get a big creature out of your hand for a cheaper reanimation spell, allow you to set up evasion with a creature like Filth, or just turn that land you dont need on turn 10 into whatever the biggest threat in your graveyard is instead
It flies, it has a built in Spirit Link, and it gives you 4/5 for the low morph cost of four
At the best, you can get four massive creatures for just 3 black mana and exiling some cards you didnt need from your graveyard anyways
Note: I will be primarily discussing these card's implications in non-rotating formats, so please keep that in mind