We're playing a mtg multiplayer game with 3 people (2 friends and I). Let's say player 1 has no creature on the board and no way to defend himself and 1 Life left, player 2 has some big creatures on the board and plenty of Life, and player 3 has three 3/3 creatures on the board, each with lifelink and vigilance, but player 3 doesn't have much life left (he could die next time player 2 attacks him with full power). In order to survive the next turn, player 3 has to gain life with the 3 of his creatures AND keep them alive for defense purpose) so he decides to attack player 1 with everything.
How do you apply the damage from player 3's attack to player 1 ?
We're lacking information and can't tell if player 1 will die from the blow of the first creature to damage him (thus healing only 3 life to player 3), or if all three creatures hit him at the same time, letting player 3 heal 9 Life this turn.