Our guild used the following strategy to oneshot all 3 tiers. We had only moments to spare on Tier 3, barely beat the timer. We had over 100 guildies participating in the Mission, used Mumble to coordinate.
1) Locate the Bounty bosses before kicking off the event.
Send small groups (scouts) to each zone to locate the bosses. In our attempt this can took as few as 15 minutes or as long as an hour. One boss in particular - Prisoner 1411 - has a random path all over Iron Marches and can "escape", resetting to anywhere in the zone. Sotzz the Scallywag is another one with no known path, he has over 300 spawn points in Gendarren Fields. We found the most effective way to locate the majority of bosses was to have the zone group split - 1/2 going clockwise and the other half counterclockwise throughout the zone or known path. The bosses do not appear on your map, they have a sheriff star icon that you see ingame when you get in very close range.
2) Stall the boss at a waypoint if possible.
Some of the bosses will stop to talk to you if you interact with them. If you can stall them at a waypoint you can get to it quicker when you start the event.
3) Guild Leader kicks off the event.
When the event is triggered the Guild Missions tab shows which bosses are your targets. Have teams identified for number of bosses and coordinate. 15 minute timer starts.
4) Split the team into groups to defeat the bosses.
Tier 1 - 2 teams
Tier 2 - 3 teams
Tier 3 - 3 teams (2 bosses for each team)
Teams waypoint to their respective target locations.
5) Start the encounters.
Once the teams are at the target boss locations, any guild member can start the boss encounter. If any guild member is not present they will not receive rewards, coordinate so that all participants are ready. As each boss is defeated, the teams WP to the next boss, coordinating efforts to groups that need the most help.
6) Boss strategies (work in process)
Take particular note of boss abilities and aura fields. Some bosses have a confusion type ability, some have a field which they need to be knocked out of before they take damage.
Ander “Wildman” Westward - is trapped inside a Veteran Karka. Kill the Karka to release the boss
Devious Teesa - Pulls in, use condition removers to remove cripples
Diplomat Tarban - Use condition removers and turn off auto-attack to avoid confusion damage
Half Baked Kamali - scales ridiculously, the fewer fighting him the better
Prisoner 1141 - Use speed buffs for your team and cripples to slow the boss when he runs
Sotzz the Scallywag