This accolade is earned by disabling the Watcher Archon (four legged mech) and then using the melee finisher on its tail (not its head). Follow the button prompts to complete this task.
InstructionsCONTROLS: GROUND CONTROLS;
Left Bumper = throw grenade;
Left Trigger = aim weapon;
Right Trigger = reload;
Right Bumper = primary fire;
Left Thumbstick = move;
Back Button = view waypoint objective;
Start Button = pause menu;
Y Button = take flight;
X Button = take cover;
B Button = pick up weapon, melee, enter turret, enter freefall (while hovering);
A Button = hover;
D-Pad = switch weapons;
Right Thumbstick = move camera;
COVER CONTROLS;
Left Thumbstick = move between cover;
Left Thumbstick Up = vault over cover;
Right Trigger = blind fire;
Left Trigger = aim over;
X Button = leave cover, drop, vault to ledge;
MENU CONTROLS;
Left Thumbstick or D-Pad = navigate menus;
A Button = confirm selection;
B Button = previous screen;
FLIGHT CONTROLS;
Left Bumper = lock-on to enemy;
Left Trigger = secondary fire (if available);
Right Bumper = flight freecam;
Right Trigger = primary fire;
Left Thumbstick = steer;
Back Button = view waypint objective;
Start Button = pause menu;
Y Button = boost;
X Button = brake;
B Button = skyjack, enter turret;
A Button = enter hover;
D-Pad = look at surroundings;
Right Thumbstick = roll
Control infoGamepad/Joystick