give 0 XP for a kill.
It's already 0 XP for a kill any NPC in town, or else I would lvl up on Sha Enin after wipe.
Make him insta-respawn.
Or he should have 9999 HP and a Solar Scorcher equipped, which, as we know, reloads by itself.
Then it'll be easier just to disable attacking those NPCs and make them immune to any damage, but... it will be not FOnline.
Izual or someone already buffed Sha Enin after I killed him many times for some time (looks like now he's 50 HP again), so yeah, any GM can just increase his HP, but Chris is alone... with no guards, no HP will help him, I think max HP possible won't last long from few avenger bursts in point blank, so it's useless for him, making him 100% DR and 999 DT and immune to crit effects is.. again, it's easier just to disable attacking NPCs.