Bah, j'ai envie de dire, c'est les règles qui expliquent que ça marche comme ça xD
La Chain Reaction se résout et inflige, disons, 15 blessures à chaque créature, dont 5 que tu contrôles, et du coup elles meurent toutes. Du coup, la capacité de Blood Artist se déclenche 15 fois et celle de Outpost Siege 5 fois (si t'as choisi dragons bien sûr)
Les créatures meurent en même temps, donc Blood Artist meurt aussi, mais Blood Artist voit tout le monde mourir et sa capacité se déclenche pour chaque, c'est comme ça quoi xD Il meurt pas avant ni après, quoi.
603.10. Normally, objects that exist immediately after an event are checked to see if the event matched any trigger conditions, and continuous effects that exist at that time are used to determine what the trigger conditions are and what the objects involved in the event look like. However, some triggered abilities are exceptions to this rule; the game “looks back in time” to determine if those abilities trigger, using the existence of those abilities and the appearance of objects immediately prior to the event. The list of exceptions is as follows:
603.10a Some zone-change triggers look back in time. These are leaves-the-battlefield abilities, abilities that trigger when a card leaves a graveyard, and abilities that trigger when an object that all players can see is put into a hand or library.
Example: Two creatures are on the battlefield along with an artifact that has the ability “Whenever a creature dies, you gain 1 life.” Someone casts a spell that destroys all artifacts, creatures, and enchantments. The artifact’s ability triggers twice, even though the artifact goes to its owner’s graveyard at the same time as the creatures.