At lvl 20, fb+vs+leap is the only viable build if you want to be able to compete against other lvl 20s, so yes, this game is really that badly designed (but not to say that they can't fix it).

So. You'll have:
Unholy Force x1
Hellblade x1
Leap x1
Fatal Burst x1
Curse x1
Vermin Swarm x1

Vampiric Strength x2
Vampiric Vitality x1
Sanguinary Wrath/Blood Shield x1

Or alternatively Drop the Wrath/Shield for Shadow Dance.

As far as stats go, the standard seems to be 100 damage, 130 defense, 1000 health.