The eight buffed archers should hold all lanes while you take care of the boss. If you have problems with mobs hitting your core, don't place the the one SA at the core and remove the boss archer, use that DU to place three squire dummies on the lanes near the core.

When you kill the lava mini bosses, he will drop the molten ball, take that to the catapult and activate the catapult, that will make the boss "drop" and now you can damage him for a shot amount of time. Just repeat the until you do enough damage and the wave ends.

Be sure to focus upgrading the archers that are looking at the hard lane.

I tried this build with a much weaker huntress dps that I have, it took me more than double the time, but the build worked.

If you have any questions about the build or the map, ask below or PM me.

To spawn the chest, you have to activate the six books that can be found on the map. Once activated, the chest will spawn and it will open itself when the boss dies.