Business Rivals | Divinity Original Sin 2 Wiki

Grog the troll, a brutish monster keeping a desolated bridge, asked us to get rid of his competitor, Marg the troll

Talk to Marg, decide if you want to kill her or take her offer and kill Grog. You can find her on the bridge between the Cloisterwood and the Driftwood fields.
Tell Marg that Gorg asked you to get rid of the Competition, Gain 13450xp
Kill Marg gain 14450 xp
Tell Gorg that marge is dead 13450xp (Optional, if you still wish to do step 5 immediately attack Gorg after recieving the xp)
Kill Gorg gain 38800 xp

Grog is a very strong enemy that can one-shot weaker characters.
Use the Polymorph skill Terrain Transmutation to bring up deathfog from the Cloisterwood docks and teleport it on whichever troll you're fighting in your first turn.
If you wish to fight them head on it is reccommended to leave this quest until just before you leave Act 2

Remove Competition
Grog the troll, a brutish monster keeping a desolated bridge, asked us to get rid of his competitor, Marg the troll
Competition Removed
Marg the troll is dead.
Grog Moved
Grog has left his bridge to take control of a better one. Before he left, he gave us something for our efforts.
Grog Is Dead
Grog the troll is dead.
Told Marg Grog Dead
We told Marg that Grog was dead. She rewarded us.
Paid Grog
We paid the toll that Grog demanded, but it didn't do much to improve his temperament.
Counter Offer
After learning of Grog's request, Marg the troll, a seemingly much nicer troll, asked us to get rid of Grog instead.
All Dead
Both of the trolls are dead. There's nothing more we can do about this matter.
Close Left R C
We have left Reaper's Coast, without fulfilling Grog's request.
Close Left R C Reward
We have sailed on from Reaper's Coast, with informing Grog that we fulfilled his request. That's one reward we'll likely never be able to claim now.