Stage 20 dungeons. 

I wanted the 6* gear to be able to get to dungeons 20.  The answer is always 2 steps ahead and around a bend in the road.   lol

@Daering, thanks for your help. 

Try to improve on the dragon. You will get 6-star gear from stage 13 and the speed and vampire sets are really good.

Try to improve on the dragon. You will get 6-star gear from stage 13 and the speed and vampire sets are really good.

I am steadily piecing together a CB team out of what I have.  Is there any special weakness I should target on the Dragon to have more success? 

poison

Stacking big amount of poisons, champions with hit, based on enemy max hp, generaly hard hitters. Having Dragon debuffed is important (turn meter stuff didn't work on him). You will have good amount of debuffs on your team as well. 

Generaly, think of it as damage race. Hit hard, hit fast. On some stages the adds before the Dragon can be more difficult than the boss himself. Still, this is probably less difficult than any other dungeon.