Keep Researching Until You Get Above The Expedition Research Node.
- This Spawns The Sarlacc Event. (Root Of The Problem)
Hit It With Lightning, It Will Retreat Back Underground.
- Wait For It To Pop Back Up And Hit It Again.
- Do This Like 5 More Times About Once Per 30 Seconds. (Whenever You See The Health Bar Pop Back Up)
Achievement Pops When It Dies.
Side Note*
To Complete The Attatched Quest: After You Kill It, The Research For The Second Part Of The Quest Unlocks.
Drop What You Are Researching To Finish It Fast; Because You Need To Build The Associated Buiding, Before The Quest Timer Ends.
Good Luck!