By "ruin" your character, do you mean "You still delete your character
WAY before age death would hit"? Because in practice, that's how that
goes for 95%+ of orcs.

My official suggestion would be - if you know you're fighting a wither-
happy shaman, make sure you keep your wisdom maxxed and gear for saves.

Pretty much the same suggestion I'd give for fighting a transmuter, who
is more likely to ruin your character via inching you closer to condeath
than a shaman is likely to impact age death on your orc.