Trials are challenges that are unlocked upon completing a level for the first time. The trials can be done on any difficulty and each level contains one. One thing worth mentioning is Warrior difficulty fills your health bar to half after death on a reload whereas Paladin doesnt which can make things much easier as well but obviously means you need to play the level more times. I do recommend using a controller instead of keyboard.
Besieged Village
Trial: Defeat the level without having any of the 3 Villiagers die.
This is best done on a regular difficulty if you arent adept at the harder difficulty. Simple just beat the level without any villagers dying. The first section is pretty straight forward. Kill the Lesser Lycans before they attack the villagers. They go gown pretty quickly. The tougher portion is the Warg. Relentlessly attack the Warg, if you can block and counter his attacks he will go down fast. The only trick here is to impale the Warg on the first try.
Hunting Path
Trial: Complete the level without healing by any means
Pretty straight forward. Level itself isnt that long. Make sure you start the level with full health. There are two fighting sections. First is just some Lesser Lycans, the second is a Warg with Lesser Lycans. Fights nor nothing new, just block or dodge and get those health bars down. When the Warg's health is near or at 0 it will be stunned and you will have to QTE to mount it. Just to reiterate this also means Light Magic is not to be used or you will fail.
The Dead Bog
Trial: Complete the level after defeating 50 Goblins.
Another straightforward one. Simply advance as normal until the section where you need to grab the bombs and throw them at the tree to knock it down. Instead of picking up the bombs just kill the goblins and they will keep respawning until the tree goes down. Once you hit 50, knck the tree down and continue.
Pan's Temple
Trial: Complete Pan's trial in 5 moves
Answer: Outer Ring Clockwise x2, Inner ring Clockwise x2 and Middle ring Clockwise x1
Oblivion Lake
Trial: Defeat the Ice Titan in 1:30
This one is a bit difficult. The one thing you absolutely need is the Dark Crystal. The Dark Crystal will knock the Titan's health to 25%(approximately) and at this point each rune requires only 1 hit. The timer will not start until you are able to grapple him or in some cases use the Dark Crystal too early.
To start charge at him dodging his attacks. He always starts with the straight line ice attack, if you are fast enough you will close enough that he cant use his ice enclosure attack. If he uses it just spam your area attack to break it. When you are close he will punch the ground. Jump as he does so to avoid damage, once he punches the ground once, use the Dark Crystal. When he punches the ground the second time it will get stuck and the timer will start.
Grapple his arm to attach and quickly clime up to his rune. Be ready to hold the button or key required when he tries to shake you off every 10-15 seconds. You are going to need to get familiar with all the ledges, rune locations and post rune destruction attacks. The Autosave does not work in your favor here so you need to be flawless. I think it is after the 2nd rune, you hit an autosave in which case when you load the save you are at the start of the battle with whatever time you had left.
On the longer ledges make use of the ledge jump which is direction + A. After destroying the first rune dodge side ways when he tried to hit you with his other hand and grapple it to get on his hand and as his hand moves back you can grapple his chest. Grapple it and move to the next rune. Once broken, grapple his chin to get onto his back. Quickly make your way down and destroy the rune. Quickly move up to the top of his back just under the head and you will be able to grapple the back of his head. Once there you can quickly move to the last rune at the side of his head.
It is a pretty difficult trial, I only managed to beat it with a second to spare.