Rodeo-killed a Titan

To "Rodeo" an enemy titan, you simply need to jump at it. If you are close enough, you will automatically climb onto its back and open a hatch to reveal its weak spot. Using your primary weapon, fire repeatedly until the titan goes into its "doomed" state at which point you can jump off and wait for it to explode. Don't use an anti-Titan weapon while mounted, you'll die! The Charge Rifle is the exception to that rule.

You do not have to take off the entirety of a Titan's life for this achievement, only "doom" it, so look for weakened Titans that are preoccupied fighting your teammates, or Titans in guard mode that have been left by themselves. Using Stim in your Pilot loadout will allow you to heal through a smoke counter-attack, and using the Spitfire LMG with the Slammer mod will destroy even an Ogre Titan quickly.

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