Oloro, Ageless Ascetic is banned as a commander in Duel Commander format, but it may be part of your deck.

Oloro's first ability works only if Oloro is on the battlefield.

If Oloro is your commander, its last ability will trigger at the beginning of the upkeep step on your first turn.

Oloro's second ability triggers just once for each life-gaining event, no matter how much life is gained.

You decide whether to pay {1} as the second ability resolves. If you do, you'll draw a card and each opponent will lose 1 life.

If two creatures you control with lifelink deal combat damage at the same time, Oloro's ability will trigger twice. However, if a single creature with lifelink deals combat damage to multiple creatures, players, and/or planeswalkers at the same time (perhaps because it has trample or was blocked by more than one creature), the ability will trigger only once.

In some unusual cases, you can gain life even though your life total actually decreases. For example, if you are being attacked by two 3/3 creatures and you block one with a 2/2 creature with lifelink, your life total will decrease by 1 even though you've gained 2 life. Oloro's second ability would trigger.

In a Two-Headed Giant game, life gained by your teammate won't cause the ability to trigger, even though it causes your team's life total to increase.