@Ing256 your maths is not quite correct. You are right that the probability of palp stunning a single toon with his aoe is 0.7 x 0.85 = 0.595 = approx 60% (probability of proc x probability of not being resisted).
Assuming we then have 5 enemy toons you need to do a simple binomial calculation ('k' successes from 'n' trials; for simplicity I assume a 60% chance of a 'success'):
probability of 0 toons being stunned = 0.01024 = approx 1%
probability of 1 toon being stunned = 0.0768 = approx 7.5%
probability of 2 toons being stunned = 0.2304 = approx 23%
probability of 3 toons being stunned = 0.3456 = approx 35%
probability of 4 toons being stunned = 0.2592 = approx 26%
probability of 5 toons being stunned = 0.07776 = approx 8%
So you have an 84% chance of stunning between 2 and 4 toons. Good odds!