The Curse of Eelgrass Bog by Mary Averling

And also, there might be an answer down there as to what is up with Greg's dad. He lets Greg know that there's a huge gathering of elves down in New Orleans that are up to something bad. Stoney tells them all sorts of interesting things (and expands their vocabulary). But they are successful recruiting a Rock Troll named Stoney who used to be a slave of the elves. They are supposed to try and recruit the creatures, but most try to kill them before they can even talk.

Greg and his friends are trying to survive being sent out on MPMs (monster pacification missions) because there aren't enough adult dwarves to handle all the monsters entering the world with the resurgence of magic. Can Greg and his bloodthirsty talking ax keep them out of harm's way long enough to prevent all-out war? Or will epic failure find him yet again in this hilarious, action-packed sequel to The Legend of Greg? Before they can say 'Galdervatn,' Greg and his Dwarven friends find themselves up against perilous dangers that their training has barely prepared them for. To make matters worse, rumors are growing that the Elves are planning a sinister attack-and their new leader might be none other than Greg's former best friend, Edwin. But now that magic is spreading rapidly, calling forth mythical monsters that are wreaking total havoc on earth, he knows things will never go back to normal.

Greg Belmont longs for the days when he thought he was an ordinary thirteen-year-old, before he learned he's really a fantastical Dwarf in a world where the return of magic has reignited an ancient feud between the Dwarves and the Elves. Magic and mayhem collide in this monstrously funny middle-grade sequel to Chris Rylander's The Legend of Greg

The Curse of Eelgrass Bog by Mary Averling