100 HP at level 8 and you complain about being 2 shotted?
Let me add this up.
32=8*4 for wizard levels
20=heroic vitality
16=8*2 base con of 14 (worst case scenario for a first life drow)
16=8*2 bears endurance (not possible to get a +5 item)
10=toughness
20=toughness enhancements
10=false life item
=124
Additional options ...
10=improved false life
10=pirate cove necklace
8=+2 con tome
Finally ...
11=aid potion (temporary)
13=false life (spell, temporary)
No level 8 wizard should have only 100 HP, this isn't a problem with game mechanics but a problem with your build.