How to calculate total chance from different simultaneous chances

Not quite sure how it works, but if it's 5% per cast then it's...well, 5%.

However, if it's 5% per hit (regardless of whether the skill drains only once or otherwise)...

P(4 activations) = (0.05)^4 = 0.00000625
P(3 activations) = (0.05)^3 = 0.000125
P(2 activations) = (0.05)^2 = 0.0025

Also:

X ~ No. of activations, out of 4.
X ~ B(4, 0.05)

P(X greater than or equal to 1) = 0.81450625

p.s. simply put, the last one is the probability that Dragon Wisdom would activate at least once per 4-hit Buster.

this is exactly what i'm asking, how to know the chance of at least one of them activating, i was also thinking of the gambler's fallacy, but for some reason i kept thinking there's a way, the above example would be about all of them activating, i am wondering the second part, how to calculate the chance that an individual one would activate.

i am still unsure if it's possible though.

EDIT: forgot to add, yes, it's 5% per hit, meaning crusher on one target has 4 hits, 4 chances of it to activate. 3 targets would be 12 hits, and so