Achan hiArusa
Explorer
Strangely enough, my players don't use them. Whether its because its the fact that they are leaving victory to a single die roll, out the desire for honorable combat, or because of bad memories of me using them on them (Circle of Death in a CoCd20 game), they just don't. For some reason high damage spells like disintegrate are more fun for them than save or die spells. When they cheese I cheese back, which encourages better behavior. Its kinda like good parenting.
At any rate, what I've used is x5 max hit points, +2 to all saves, +5 insight to AC, an extra attack or two, a reactive attack when flanked, and a massive attack that is triggered when they are at less than 50% hit points. I also give them action points as per Modern d20 as if they were PCs, but I allow the dice to stack (both for them and the players, so its more like Star Wars Force points) and allow the result to be used as healing (so 1 to 3d6 + Con modifier) or the expenditure of one can give an extra attack or move action. So I can always spend an action point against those save or die spells (so +2 + 3d6 at the levels characters have access to them).
At any rate, what I've used is x5 max hit points, +2 to all saves, +5 insight to AC, an extra attack or two, a reactive attack when flanked, and a massive attack that is triggered when they are at less than 50% hit points. I also give them action points as per Modern d20 as if they were PCs, but I allow the dice to stack (both for them and the players, so its more like Star Wars Force points) and allow the result to be used as healing (so 1 to 3d6 + Con modifier) or the expenditure of one can give an extra attack or move action. So I can always spend an action point against those save or die spells (so +2 + 3d6 at the levels characters have access to them).