Here is the full list of all 51 Trine 2: Complete Story (EU) trophies - there are 42 bronze, 5 silver, 3 gold and 1 platinum.
Earn all Trophies in Trine 2
Complete the game on hard using hardcore mode
Kill an enemy with an airborne object tossed with the Knight's charge
Kick five enemies of the same kind into a bottomless pit with the Thief's grappling hook kick or the Knight's Kitesail Shield glide kick
Capture a goblin in a Monster Prison and then launch it with a catapult
Create a makeshift raft of three separate parts and have a goblin sail it for five seconds
Launch an object with Knight's magnetic shield and break it with hammer before the object touches the ground
Capture three different types of enemies inside boxes and stack them on top of another
Throw a box with Pontius' magnetic shield and catch it or have another player catch it
Make a bubble sink for three seconds
Collect all experience pickups in the game
Complete Goblin Machinations
Complete the game
Complete Cloudy Isles
Find all chests in the game
Complete Brackenridge Rise
Complete Belly of the Beast
Complete Deadly Dustland
Make a sandworm kill another sandworm
Complete The Heroes Return
Kill a grenadier goblin with its own cannonball
Complete The Final Chapter
Complete Icewarden Keep
Complete Eldritch Passages
Complete Searock Castle
Complete Mushroom Murk
Complete Mushroom Caves
Complete Hushing Grove
Feed carnivorous plants with three or more different kinds of treats
Complete Shadowed Halls
Finish a level without taking any damage (except in the Story Begins)
Complete a level with only Pontius
Complete a level with only Amadeus
Shatter three frozen enemies within one second
Freeze two enemies and stack them on top of each other
Glide for five seconds with Kitesail Shield while having an object or character on top of the shield
Construct a tower made of eight objects and stand on top of it
Stand on a plank floating on a single airflow for four seconds
Using grapple, swing around an object and reattach grapple again without touching any surface
Get at least 10 enemies killed by other enemies' actions in a single level
Complete a level with only Zoya
Kill an enemy with a thrown hammer bouncing at least once before kill
Complete Petrified Tree
Build a three-piece or three-character tower where lowest part is Pontius and his shield, tower must stand at least five seconds
Stand on a conjured box bouncing on any bouncy surface for 10 seconds
Shoot three arrows in the air and catch them all with the Knight's shield
Complete Mosslight Marsh
Complete Mudwater Dale
Make goblins die of three different environmental hazards in a single level
Complete Forlorn Wilderness
Complete The Story Begins