BioShock 2

A Trial is best described as an in-game challenge that will allow you to gain more ADAM in the game. The benefits of completing trials are obvious as it will help you to level faster and it also gives you something to do if your bored of playing the game normally. You can only complete these trials online and it has to be in a public match as well.

Trials are split into three groups:

Group one "weapon trials"

Weapon trials are very simple and at the beginning will only involve you scoring 30 kills on enemy splicers (other players). But they also become more difficult after you start leveling up, for instance one of the harder ones is for scoring a Grenade launcher kill on an enemy while they're in the air.

Group two "plasmids/Combo Trials"

Don't worry about the long name this isn't harder than the group one section in-fact; most are easier. To complete trails in this section you will need to master the use of plasmids in combat and it will also serve as a good structure to get you combining your plasmids.

Group three "General trials"

This is probably going to be your least visited section as you only unlock a couple of trials each couple of levels and they are also trails that just come from playing unlike the other trials. This has the easiest Trial out of them all to get the achievement as all you need to do is kill someone who has a picture of you.

Remember if you need to check what you need to do next just go to the multiplayer menu and click on statics>Trails then just pick a section and your good to go.

If you have any questions just send me a message and ill be happy to help.

The trials are basically just special things you must do in a match to earn bonus ADAM. For instance x kills with a certain weapon. The easiest one to do, at least when you start, is using your plasmid. You have to hit someone 30 times. (You don't have to kill anyone, just land 30 hits on people.) You have to do this in a public match, as the description says, but its not hard if you can land a single hit on someone. So just use a single plasmid until you get this.

Trials are completed like challenges in multiplayer for bonus experience points.
Some easy one are to kill 30 people with each weapon and plasmid, they get more difficult as you go on.