There are 12 Trophies that can be collected.

BRONZE

Breakout
Destroy 50 wall segments using only fireballs

Fish In A Barrel
Destroy 50 troops using only fireballs

Siege Engine
Destroy 50 wall segments using only troops

Master Mason
Repair 50 wall segments back to full health

Savior Of Ataria
Complete the single player campaign

Divine Intervention
Get the White Knight Shield 50 times

An Eye For An Eye
Destroy 50 troops using only your troops

SILVER

Warlords Fever
Win 103 matches

Control Freak
Own all powerup pads in a 4 player game at the same time

Power Is Everything
Obtain 50 powerups

Defender of The Weak
Banish the Black Knight 50 times

GOLD

Just Barely
Win a game with no wall segments left

http://www.ps3trophies.com/forums/playstation-trophy-news/23661-warlords-trophy-list.html