Mikaeus, the Unhallowed. He makes a stupidly too good EDH general already. Get this on the board, and your creatures will never die. It's a more powerful combo than just using Avacyn, Angel of Hope because -1/-1 counters or "becoming -1/-1" until end of turn won't ruin your day either. Only being removed from the game or countered before entering the battlefield will do it completely. And in EDH, they can only run one Final Judgement. Bouncing will delay you, but not the biggest deal. Run some cards with Unearth if you're worried about being countered.
Posted By:
Bobth
(8/13/2012 9:20:12 AM)
Crazy card with evolve (esp. In EDH). Creatures come back, evolve back to the +1/+1 range, and suddenly are ready to persist again.
This card used to be kinda funky and cool, but now that undying and evolve are here, this thing has some many fun uses.
Posted By:
Hashbeth
(2/7/2013 2:18:58 PM)
Well, Shadowmoor certainly wasn't a bad set, although I'm kinda biased since I was introduced to Magic with that set.
Cauldron of Souls works well with Heartmender, as was said before, and there are several ways to get rid of the counters as well. Considering the fact that the activation cost is a mere tap, it's really not that bad.
The Cauldron also works pretty well with the older Modular and Graft keywords.
Added: I recently constructed a deck with this and Cauldron Haze, using it to bring back creatures that can sacrifice themselves (all Wizards) and Sage of Fables to negate the -1/-1 counters to allow re-use.
Posted By:
Belz_
(6/18/2010 4:02:42 PM)
Fun with Undying creatures, like Vorapede.
Wait, what?
PROTIP: Just alternate between Persisting it and Undying it.
Posted By:
Ragamander
(1/16/2012 12:33:07 AM)
Lots of fun combos here.
With a dingus staff in play, and a mass kill spell (flamebreak, wrath of god, hurricane, etc) they take a lot of damage. Then they all come back, and everything with a toughness of one dies again for more damage.
Posted By:
psyklone
(10/28/2009 4:24:09 PM)
Great card for slow formats like 2hg, 3hg, ffa or edh/commander.
It makes your guys leave-play and come-into-play abilities trigger twice. Witness regrowths you two cards, solemn rampant growths for two lands and draws you two more etcetc. Creatures that come into play with +1/+1 counters, like triskelion, spikes or graft creatures, can be persisted with this card any amount of times. Not to mention that your guys are harder to remove as well.
You can also use it on your opponents creatures when you have horobi in play or whatnot.
Posted By:
majinara
(12/15/2009 6:01:00 AM)
Combos with Allies :)
Posted By:
iSlapTrees
(12/3/2010 1:00:38 PM)
I also think that it's not the cheapest artifact out there, but the effect is definitely useable since it does not require anything but tapping.
Like that you can save any x/2 creature wanted once and evetually trigger its cip/etb effect a second time.
And as Belz already said, this card does a great job in a deck running creatures that enter the battlefield with +1/+1 counters on them, since this means the -1/-1 counter gets negated by the +1/+1 counter, and if the creature has still one left, it can be saves with persist repeatedly.
Keep in mind that the returned card is treated as a completely new creature - that's why the cauldron didn't simply read "creatures you control gain persist until end of turn", since this would have meant an easy loop with accordant cards.
Acrbound and Simic creatures are such cards. Any guy with Modular/Graft 2 or more can be saved each turn.
Other usable creature with the Caudron are creatures with Amplify, Bloodthirst, most au... (see all)
Posted By:
Mode
(8/10/2009 7:30:07 AM)
maybe run with Ravenous Baloth, Wirewood Savage, and Aether Charge in 
Beast tribal for tons of fun?
Posted By:
Paleopaladin
(9/25/2010 10:19:44 PM)
This is amazing in a Simic deck. The -1/-1 counters will be negated, making it very hard to kill anything of yours. You also don't need to worry about your creatures running out of +1/+1 counters from overusing Graft, as your creatures will just come back again once they run out of counters.
However, people seem to forget that once the creature goes to the graveyard and then comes back it no longer has persist, it's treated as an entirely new creature.
Posted By:
JL2736
(12/1/2011 8:40:38 PM)