You have Royal Guard in your vault... get him out of there, and get him maxed out. INSANE dps on bosses, and he brings both an AOE 60% def down, and a 30% speed down. Bellower can replace Kael as a speed farmer, but I have not bothered, because we are talking about the difference of 10 seconds on most fights between my two.
The rest of this stuff are things I wish people had told me when I was at your level and stage of the game... its free advice, so its worth exactly what you paid for it... but it might help you, if you are interested...
NOW is the time in the game that you will want to start focusing on one dungeon at a time. Get a team where you want it, max out the dungeon or event they are built for, and then move on to building your next dungeon team. You are probably flying high because you have a few good champions, and get get to 14 on some of the dungeons... but the game is going to start getting a lot harder, and you will need to special craft your teams to get the most performance out of each team in each different dungeon.
For me, I found the best-ish team order to build was:
1- PVP rank -- When you can get into the silver and gold ranks, you are getting massive, across-the-board bonuses for your teams, which will be KEY in doing well in all of the other areas.
2 - Clan Boss -- You will want to be able to do Nightmare in 3 keys or less is the goal for many guilds. I am not a pro in this game, so I am sure some might disagree, but the gear, potions, rare/void/sacred shards and gems that you win from the top treasure chests are a big help in outfitting teams and building rosters.
3 - Spider -- Never underestimate the power of good accessories in this game. A single ring made 1million damage difference in CB for me in the early days. That was an extreme case, but not uncommon. You want rings, necklaces and banners on every champion you bring into a non-campaign dungeon.
4 - Dragon/Fire KNight/Ice Golem/Minotaur whatever you feel works best for you... god knows I have not figured it all out yet.