Here is the full list of all 12 Iron Sea Defenders trophies - there are 7 bronze, 4 silver and 1 gold.
Complete all levels with 3 stars
Get 100 000 coins
Kill 50 000 enemies
Sell 500 towers
Build 1000 towers
Fully upgrade 200 towers
Kill 500 enemies with the secret weapon
Sell 50 towers
Launch 100 waves on one map manually
Complete level when your castle has 1 HP
Kill 1000 enemies
Build 50 towers