Ideally, be able to target one of multiple possible things to damage, and target it to a point the foe is quickly overwhelmed, dead unconscious helpless or catatonic. Combination of Highest Possible Damage / Varied Types / Pierce Defenses - you strike their weak point for massive damage - this is going to be ability damage more often than elemental, elemental lets you strike their Not-Strong point more often.
Being made of glass will, as mentioned, take care of itself. If you want to survive being made of glass, mobility is helpful, whether that's ranged or rideby flying charge at 300'. Mostly you want to get as far out of the strike-back zone as you can afford, even if you oneshot monsters have friends.