In a game, the combo was Grumgully + Putrid Goblin + Skirk prospector + any other card that deals 1 damage to any target when one creature dies.
So the adversary sacrifice putrid goblin with Skirk, the other card deals 1 damage, putrid goblin has no "-1/-1" counter and comes back to battlefield, but grumgully gives it a "+1/+1" counter and putrid comes back as a 2/2 because of the two counters, but counter does not appears on Putrid goblin and so the combo can continue.
As -1/-1 and +1/+1 counters are different, putrid golbin should come back, but have the two counters on it, and so stop the combo.
In a game, the combo was Grumgully + Putrid Goblin + Skirk prospector + any other card that deals 1 damage to any target when one creature dies.
So the adversary sacrifice putrid goblin with Skirk, the other card deals 1 damage, putrid goblin has no "-1/-1" counter and comes back to battlefield, but grumgully gives it a "+1/+1" counter and putrid comes back as a 2/2 because of the two counters, but counter does not appears on Putrid goblin and so the combo can continue.
As -1/-1 and +1/+1 counters are different, putrid golbin should come back, but have the two counters on it, and so stop the combo.