Beacon of Immortality in exile (exiled by Spellbinder).
All permanents on the battlefield.
Light of Promise attached to Sage of Hours.Spellbinder attached to a creature that can attack this turn and that cannot be blocked and killed by an opponent.
Your life total is at least 5.
Steps
Deal combat damage to an opponent using the creature that has Spellbinder attached.
Spellbinder triggers, casting a copy of Beacon of Immortality without paying its mana cost.
Resolve the copy of Beacon of Immortality, doubling your life total.
Sage of Hours triggers, putting a number of +1/+1 counters on it equal to the life you gained.
Activate Sage of Hours by removing all +1/+1 counters from it, causing you to take at least one extra turn after this one.