The Heroes Round Table

Is it possible to alter the specialities that heroes has? For example, Lucretias Vampire Princess, gives +1 in luck and -2-3 in defense/offense.
I'd like to change that 1+ in offense/defense to something else, but I wonder, is it possible?

I will appreciate all answers.

You can swap hero specialties and skills but can't alter or create new ones. So you can drop Lucretia's Vampire bonus and replace it with Markal's Death Lord ability, but you couldn't change her ability to affect Liches instead.

Ah, ok. That's a little sad. I had hoped that it would be possible to change it so it gave more in bonus to offense, but less in defense.
Thanks, Arstahd.