Level 5 - simply reach level 5 by playing any game mode that provides experience such as versus, horde, beast, or arcade modes. The fastest way to level is to play the end of "House of sand" (2-2). Just before the end of the level, while standing by a gate, you will get a checkpoint. Once you have it, run through the gate and up the hill to finish the chapter. Then reload checkpoint and repeat this process to gain XP and a bunch of Onyx medals.
Level 10 - simply reach level 10 by playing any game mode that provides experience such as versus, horde, beast, or arcade modes. The fastest way to level is to play the end of "House of sand" (2-2). Just before the end of the level, while standing by a gate, you will get a checkpoint. Once you have it, run through the gate and up the hill to finish the chapter. Then reload checkpoint and repeat this process to gain XP and a bunch of Onyx medals.
Level 15 - simply reach level 15 by playing any game mode that provides experience such as versus, horde, beast, or arcade modes. The fastest way to level is to play the end of "House of sand" (2-2). Just before the end of the level, while standing by a gate, you will get a checkpoint. Once you have it, run through the gate and up the hill to finish the chapter. Then reload checkpoint and repeat this process to gain XP and a bunch of Onyx medals.
Level 25 - simply reach level 25 by playing any game mode that provides experience such as versus, horde, beast, or arcade modes. The fastest way to level is to play the end of "House of sand" (2-2). Just before the end of the level, while standing by a gate, you will get a checkpoint. Once you have it, run through the gate and up the hill to finish the chapter. Then reload checkpoint and repeat this process to gain XP and a bunch of Onyx medals.
Level 50 - simply reach level 50 by playing any game mode that provides experience such as versus, horde, beast, or arcade modes. The fastest way to level is to play the end of "House of sand" (2-2). Just before the end of the level, while standing by a gate, you will get a checkpoint. Once you have it, run through the gate and up the hill to finish the chapter. Then reload checkpoint and repeat this process to gain XP and a bunch of Onyx medals.
Judge, Jury, and Executioner - executed your enemies with variety and style - Normally, you would do this in online multiplayer but there you have to unlock the executions. You can also do it in standard campaign and then clean up any that you miss online but you can do all of them in campaign so just keep your eyes open. The list is:
Curb Stomp - Press Y (don't hold) near downed enemy. face Punch - As COG, Hold Y with the Snub pistol arm Rip - As Locust, Hold Y with the Snub pistol captive - Hit X near a downed enemy and then press x again to kill them lancer Chainsaw - Hold B to rev chainsaw, then run into any bipedal enemy. Retro Charge - Hold B to start a retro charge and collide with enemy when bar is red.
These all require you to hold the weapon and to hold Y over a downed enemy:
Mauler Shield Hammerburst Boltok Pistol Longshot lancer Gnasher Gorgon Pistol Boomshot retro Sawed-off Torque Bow Digger scorcher Hammer of Dawn One Shot Mortar mulcher Cleaver
