To unlock the Jager Bomb trophy in Assassin's Creed III Remastered, you will need to kill 10 Jagers whilst being fully notorious.
During Sequence 5-2, you will have to kill some shooters on rooftops. Once you do this, you will automatically reach the max level of notoriety and Jagers will start to attack you. When they attack, use
+
to perform a counter and then use
to attack.
If you don't get 10 kills from the initial wave of Jagers, find another group of enemies and fight them until more Jagers join the fight.