How good is anti venoms sig ability

ark2099

I have a choice to get new viv vision or to awaken anti venom ...but im not understanding how worth it is his sig ability like the regen is ok but not very important but the exercabate passive is it a flat 25% inc with each debuff with 10 of those or it is 25% increase in 12.5 or 16.5% meaning just 3 or 4% increase....can anyone clarify