If this was in play, I would never play a caster with an ASF chance. Many of the effects are flavorful, but there are some that are lethal.
Emnity with a Demon Lord, a 1 mile Planar Vortex, death with only 9th level spells being able to raise you. There are some others that might also be very bad, but I can't tell because the text ends at the line break.
Losing a spell is a risk that it might make sense to take. Risking insta-death or a TPK every time you cast a spell makes casting in armor much more dangerous. Although it could make for an interesting chaotic spell caster.