Originally Posted by

**apocalypse80**
Simple probability theory.

The chance that **any one** of x knives will trigger the effect is equal to 1 minus the chance that **none** of them will trigger the effect.

The probability that none will trigger it is equal to that of 1 not triggering in the x-th power.

So ; 1 - (1-7%)^x

For example , for 5 knives per casting and assuming all 5 hit something ;

1 - (93%)^5 = 1 - 69.56% = 30.44% chance to trigger.

And it's actually even higher than that , because every hit checks again.

So if a knife pierces through 3 opponents , it forces 3 checks.