Battle Chasers: Nightwar

Each character will unlock two levels of their bursts by reaching certain levels themselves, but their level 3 burst will require them to do or obtain something in order to unlock them. Here is how to get each of their bursts:

Gully - You will get it from the Beastmaster shortly after getting level 3 burst ability. Gully was at level 12 at the time I received it, but I hadn't been using her for a while so just keep checking back with Beastmaster until she gives it to her (I believe hers has to do with being in a certain number of battles but can't confirm that yet).

Knolan - Talk to the Enchantress and she will give you a page from Studies of the Arcane: Time Warp Lore book, so you must find the other two remaining pages. They are located as follows:

1. Studies Of The Arcane: Time Warp (2/3): When you are in Deadwatch, you will come to a mid-boss of sorts called Markron The Charred. After you defeat him, head towards the top of the scree there to find a small room with a book on the left side of it
2. Studies Of The Arcane: Time Warp (3/3): In the Stronghold, down the stairs to the left of the boss on the ground

Return to her after you have obtained all the Lore and she will unlock his level 3 burst.

Garrison - You must fight in the arena until you complete the Warrior difficulty. After you do, return to the Beastmaster and she will unlock his level 3 burst.

Calibretto - Head to Stonegrove Ruins in the Moors (looks like a house next to a lake) and go to the very back area to find the Ancient Construct Alpha. I would not take him on until you are a higher level as he is very powerful with a large amount of HP. His normal attacks can easily do up to 1200+ damage and his burst (which he can spam back to back), does about 1300+ to each character. Make sure you are leveled up with good weapons and armor, have a good healer in your party and prepare for them to be doing only that for the majority of the fight while the other two do the fighting. After you defeat it, return to Beastmaster in Harm's Way & she will unlock his level 3 burst.

Monika - You must kill 12 bomb lycelots (of any type) and then return to Beastmaster and she will unlock Monika's level 3 burst.

Alumon - You must first find Caldeus' skull in Deadwatch (it's near the end on a pole of bones) and then head to the Tomb Of Caldeus. Make your way inside to the far back part of the tomb to where there is a set of bones and place the skull there. Caldeus will return and you must now defeat him. He has extremely powerful attacks that do upwards of 2600+ damage, so make sure you are leveled up enough with very good armor and weapons before even attempting. Once you defeat him, return to Beastmaster in Harm's Way and she will unlock his level 3 burst.

Once you have all six characters' Level 3 bursts unlocked, the trophy will pop.