Mechanics
These are some observations regarding how Misdirection works. For example, multi-shot does not count as "one shot" as such. Moreover, the mechanisms seem to be:
* Shots that were Immune to the mob do not count as one of your 3 misdirects, seen in Karazhan.
* When misdirection is active, ALL attacks that happen on a tick during which ANY attack happens, is Misdirected.
* On next tick, the buff counter is reduced with the number of attacks that happened.
What this means:
* You can misdirect more than three targets with Explosive Trap (Tested in Steam Vault with the yellow slave groups of four - all were misdirected, counter just went to zero).
* Note that only the initial explosion damage is misdirected; The damage on next tick counts against the hunter again.
* If you want "optimal" misdirectioning with multiple targets, save Multishot for last (eg. Aimed shot => Distracting Shot => Multishot). The first two shots reduce counter by one, and Multishot takes it to zero even though it's hitting multiple targets.
* If, against three or more targets, you use multishot first, Misdirection counts to zero after that first Multishot since three attacks occured.