Battle tower is on Sentinel Island you get to there right after you beat the dragon. Go right out of the big cavern where you beat him and take a left I believe it is. You'll get a cut scene after going thru a door then after that have access to sentinel island.
How'd you get past those black ring guys anyways just jump over them and run out
. There is like 6 that just come running up the stairs and I and the mine guild guy get slaughtered in 10 second so I gave up after reading a walk-through, found out that is really for later in the game.
P.S. Heed the warning of the lady in your head after a certain point in the sentinel island tower. I did not at first, Luckily I had a save game right before and got myself out of not being able to complete some left over quests.
Oh and there is a teleporter right near the door to get to sentinel island, Maxos tower something.
Use that unless you have left over loot to get.
