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BG:EE - Cursed Scroll of Summon Monster is exceptionally useful for assassination without rep loss
when you cast it on a character and he gets killed, there is no rep loss. it's a great exploit because you can obtain items such as the scroll case (which either can't be pickpocketed, or it's very hard) from firebead, cloak of non-detection from ordulinian (when you don't get the quest because of insufficient rep) and gauntlets from noralee upon returning them (can't pickpocket them), etc.
this exploit should be closed. enemies getting killed in this way should count as killed by the party.
another way to assassinate characters without rep loss is charming them and having them cast their spells on them. when their own summons kill them, because the creatures count as your team, there is a rep loss, but if they cast offensive spells on themselves and die (very easy, that's how i kill shandalar's daughters) there isn't a rep loss.
this is also an exploit that should be closed, but that's more debatable i guess.