At this point, I am unclear as to how to handle encounter XP. Does each surviving party member receive a proportional share, or the full amount?
That is, assume a 4-character party had completed an encounter worth 400 XP. Would each party member receive 100 XP, or 400 XP?
Best Answer
Total XP is divided amongst the players participating in the combat
The "Experience Points" section of the Dungeon Master's Guide says (p. 260):
This rewards players based on the relative difficulty of the combat rather than the empirical size of the opposition. 10 goblins is more of a challenge to 4 players than to 10 players, for instance; thus, each player gets a larger piece of the XP. Otherwise, an army of player characters could amass absurd XP from swarming a high-CR monster and all benefit as if they had single-handedly taken it down.
In terms of survival, the DMG never distinguishes between alive or dead combatants for XP division. Thus, XP is divided amongst the living and dead with no differentiation. By nature of being a PC, players are considered as providing "substantial assistance" regardless of their actions (so long as they participate in the combat). Survival has no effect for NPCs that provided "substantial assistance" and are still rewarded XP accordingly if killed.
Thus, in your example of four players facing an encounter worth 400 XP total, each player would receive 100 XP whether they survive to the end of combat or not.