That guy is General RAAM.
He's the final boss of Gears of War.
His difficult depends upon your selected difficulty
Casual, Hardcore & Insane.
To beat RAAM, you should pair up w/ a friend and play this last level on co-op.
Player 1 should shoot torque bow arrows
Player 2 should use the longshot rifle
as soon as you begin, stay behind the cover in front of you and begin procedure:
P1 should shoot torque bow at RAAM in the head or upper body, this will scare the bats (also known as Krill).
P2 should snipe RAAM in the head as many times as possible until the Krill return to RAAM
Repeat until RAAM gets near your cover.
Roadie Run to the opposite side and repeat procedure.
You should Achieve Victory within 1min 30sec, depending on difficulty level.
Enjoy cutscenes, and gloat to your friends about your recent victory.
Hope you win.
GEARS OF WAR 2 IS AWESOME!!!