2018-12-07
If a cost would include causing you to gain life (like the alternative cost of an opponent’s Invigorate does), that cost can’t be paid.

2018-12-07
Platinum Emperion’s ability doesn’t prevent damage. Rather, it changes the results of that damage. For example, if a creature with lifelink deals damage to you, you won’t lose any life, but its controller will still gain that much life. Similarly, if a creature you control with lifelink deals damage to another player, that player will lose life but you won’t gain any life.

2018-12-07
Abilities that trigger whenever damage is dealt to you will still trigger because that damage is still dealt, even though your life total doesn’t change as a result.

2018-12-07
Spells and abilities that would normally cause you to gain or lose life still resolve, but the life-gain or life-loss part simply has no effect.

2018-12-07
You can’t pay a cost that includes the payment of any amount of life other than 0 life. However, you can choose to be dealt damage, even though that damage won’t result in your life total changing.

2018-12-07
Effects that would replace having you gain life with some other event won’t be able to be applied because it’s impossible for you to gain life.

2018-12-07
Effects that replace an event with having you gain life (like Words of Worship’s effect does) or having you lose life will end up replacing the event with nothing.

2018-12-07
If an effect says to set your life total to a certain number, that part of the effect won’t do anything.

2018-12-07
If an effect would cause you to exchange life totals with another player, the exchange won’t happen. Neither player’s life total changes.

2018-12-07
In a Commander game, the damage dealt to you by commanders will still be counted, even if that damage doesn’t cause you to lose life.