Jeep Invincibility
A great way to be both invincible and ridiculously powerful is by taking advantage of the Jeep invincibility glitch. To perform this, simply run over to a Jeep. When a message on screen prompts you to get into the Jeep, go into a prone position. Now climb under the Jeep. Finally, press the button to get into the Jeep. You are now invincible to gunfire and have access to the Jeep's machine gun. Watch out, though, as you can still be killed by melee attacks and explosions.
Invinciblity Under a Tank
To perform this maneuver, you'll need help from a teammate with a tank. While your teammate is in the tank, go into a prone position in front of it. Now crawl under the tank while your friend drives the tank forward. You will be caught underneath the tank. While there, you are completely invincible.
Invincibility Online
Using this glitch will make you invincible when you play online. However, it takes quite a bit of work to pull it off. First you need to take advantage of the zero respawn time glitch. Create a game in Battle mode, and then go to the settings and change the time limit to anything you want. Now select the game mode you want to play, such as Capture the Flag. There will not be any delay in respawns. Now wait until someone enters the game and his name appears on the scoreboard, and then immediately switch sides and then switch sides again. Finally, press respawn. You will be invincible.