These are the heroes I have and plenty of emblems to use except cleric at the moment. How should I build my defence team? Should I emblem some hero?
I also have Agwe, Sabina, Kashhrek and Skittleskull standing at 3.60 but plan on not leveling them.
Then I have Colen, Cyprian, Mist, Boril, Chao, Mok-Arr, Stonecleave and Hu Tao at 1.1. Any of them worth leveling for defence team?
Out of what you have I’d do Mist, Boril, Brynhild, (Scarlet or Grimm depending if you want to play rainbow defense) and Sartana (try to get Sartana at 4*80 asap).
Mok-Arr is good for Dark Mono, but Sartana should be priority.
P.S: you can swap Brynhild with Melendor, but I like her way better, especially when you’re able to change formation to double reverse; she is more versatile that way.
Good luck 
@Mal4uguana gives good advice. Brynhild is a fine tank when you have a limited roster. Mist and Boril will serve you well also. I’d probably do Sartana-Mist-Bryn-Boril- Scarlett.
Cheers!
Out of those, my choice considering, at what I consider is the probable level you are playing at, I’d be going with BT, Mist, Boril, Brynhild and Sartana. A bit passive, but great survivability.
I’m a big fan of BT and still use him in Diamond, Brynhild provides healing for neighbours and a mana buff which should never be undervalued. Boril makes a good serviceable tank, especially with a Brynhild flank. Sartana is a weapon. Well, that’s a rainbow.
Sabina was my first healer dispeller but needs emblems for survivability (I still use mine), Agwe is very niche and is only useful in one rare quest (shrikewood?) but only take him to 3/60. Everyone grows out of Kashhrek but at 3/60 he is serviceable but probably not worthy of ascension mats. Grimm is a bit squishy but totally useful. Chao has his place but dies easy too. Cyprian is no match for a Boril. Stonecleave is fun but will not work with BT. Forget Skittles after 3/60. Hu Tao is underrated imo… Don’t max Colen unless you get the costume. Costume Melendor is worthwhile but also dies fast. Just no to Mok-Arr and Stonecleave. Tarlak will be great when you get the mats for him.
Just my 2 gems worth. 
I would use Boril as a tank, flanked by the green healers, from leftvto right:
Scarlet, Brynhild, Boril,cMelendor, Sartana.
Brynhild keep Boril and Scarlett alive and boosts their mana generation, cMelendor boosts defense for all and heals all over time. Sartana is the sniper to finish the enemmies off. Scarlett weakens the enemy to kill themselfs firing on Boril and his flanks.
Mist is a very good hero, but with Boril snd 2 healers we need a bit more punch, therefore scarlett.
Good luck
