When that creature dies, its persist ability triggers, returning it from your graveyard to the battlefield with a -1/-1 counter on it.
Thran Vigil triggers, putting a +1/+1 counter on that creature.
Remove a +1/+1 counter and a -1/-1 counter from that creature as a state-based action.
Resolve the
Evereth ability from step 1.
Repeat.
Notes
If you have a way to kill
Evereth and ({1} magic symbol) ({BR} magic symbol) available, you can do so after putting a significant amount of +1/+1 counters on it to deal damage to each opponent using its second ability.
Results
Infinite +1/+1 counters on a creature.
Infinite creature ETB.
Infinite creature LTB.
Infinite creature sacrifice triggers.
Infinite damage.
Infinite death triggers.
Metadata
In 666 decks according to EDHREC.
Bracket Tag
This combo has been estimated to be Spicy (Bracket 3-4+).