Forum:Soul absorbing bone towerr

Question?

If you have 2 soul absorbing towers on the field and then you special summon a zombie master using a book of life for example then activate his ability discard to special summon another zombie master then activate that monsters ability to summon another zombie to the field does that mean your opponent has to discard 12 cards to the graveyard or just 2 need 2 know the answer PLEASE in need of sorting out a situation.

Thanks