| Depends what is the oppoenent in front of you.
But I am more to case first a protective spell.
Why:
1 If he launch a powerful spell it's better to be cover.
2 If that creature is quite intelligent and has dispel, it might first lauch this before anything else then you can send you bio.
The problem is Shell is no use against physical attacksk then on a monster not using magic, I'd go for Bio...
Depends the situation actually, there is no real standard to use...  Free your mind, feel your cosmo, create wonders ... |