I know Plarium doesn't take player Ideas, but I was bored and thought "How would the Potion keep bosses work as champions if they were added into the game?" 

This is what I came up with based on their appearance and skills. An thought it would be cool to make them simply Epic rarity champions, with the last one being a legendary unit (although the easiest to get IMO) an if ever implimented into the game, you'd get for clearing the last stage of the keep. All stats at 60 for the examples.

FAIR WARNING, A LOT TO READ BUT A FUN IDEA

Spirit Keeper - Sylvan Watchers Faction - Support - spirit affinity

HP- 18,980

ATK- 1020

DEF- 1280

SPD- 102

Crit R.- 15%

Crit D.- 50%

RES- 40

ACC- 0

A1- Attacks all enemies, and heals this champion and all allies 15% of the damage delt. (Booked up to 25% with 20% DMG bonus)

A2- places a 15% continuous heal buff on this champion, and 1 ally with the lowest HP (Ascended 3 star) Removes any decrease healing, block debuff, and destroyed max HP before placing continuous healing buff) (5 turn CD, Booked down to 3 turn)

A3- Removes 1 Debuff from all Allies, then heals each ally for 5% their max HP for each debuff removed by this ability. (5 turn CD, Booked into 8% Max HP {1% more per book/3 books} healing, and 4 turn CD)

Void Keeper - Dark Elf - Attack - Void affinity

HP- 15,830

ATK- 1,360

DEF- 1010

SPD- 93

Crit R.- 15%

Crit D.- 50%

RES- 30

ACC- 20

A1- attacks 1 enemy 3 times, each hit has a 25% chance to place a 5% poison debuff on to the target (Booked up to 35% chance and 15% bonus DMG)

A2- Attacks All enemies and has a 70% chance to place a 5% poison debuff for 2 turns(Ascended, Also has a 70% Chance to place a protected poison sensitivity debuff for 2 turns)(Books to 100% chance for both debuffs and 20% more DMGand 4 turn Cool down)

A3- instantly activates all poison Debuffs from all targets, for each posion debuff removed, Fills this champions turn meter by 2% (6 turn Cooldown, books into 4 turn cooldown)

Magic Keeper - The Sacred order - Support - Magic Affinity

HP- 18,000

ATK- 980

DEF- 1,120

SPD- 101

Crit R.- 15%

Crit D.- 50%

RES- 30

ACC- 10

A1- Attacks 1 enemy, places a shield on this champion equal to 15% of the damage dealt for 1 turn(Books up to 30% with 15% increased damage)

A2- Places a shield on all allies equal to the shield on this champion for 2 turns (6 turn Cooldown, books to 4 turn cooldown)

A3- Attacks all enemies, and has a 70% chance of placing a 30% decrease defence debuff on all targets for 2 turns. (books to 100% and 15% more DMG)

ASCENDED PASSIVE (At the start of each of this champions turn, this champion gains a 10% Max health shield, this shield can stack with the shield from A1)

Force Keeper - Dark Elf - DEF- Force Affinity

HP- 19,860

ATK- 920

DEF- 1,365

SPD- 96

Crit R.- 15%

Crit D.- 50%

RES- 60

ACC- 0

A1- Atks 1 enemy, has a 50% chance of placing a HP burn Debuff on the target for 1 turn (books up to 75% and 20% more DMG)

A2- Attacks 1 enemy, has a 60% chance to place a 60% decrease Defence debuff, or a 30% Decrease speed debuff on the target. (ASCENDED- becomes 100% to apply BOTH debuffs if the target is under a HP burn debuff) (5 turn Cooldown, Books to 75% and 20% increased DMG, and to 3 turn cooldown)

A3- Attacks all enemies, has a 25% chance to place a HP Burn debuff to all targets, For each active buff on this champion, the chance to apply the HP burn debuff is increased by 5% (5 turns cool down, Books to 3 turn cool down, and last book is increasing the debuff chance by 10% per active buff on this champion)

(AURA- increases allies ACC by 40 in all battles)

Arcane Keeper- Banner Lords - Support - Void Affinity (LEGENDARY UNIT)

HP- 14,040

ATK- 1,575

DEF- 790

SPD- 107

Crit R.- 15%

Crit D.- 63%

RES- 20

ACC- 10

A1- Atacks 1 Enemy, has a chance to remove 1 debuff on the target, this chance is based on this champions crit rate % (Books to have 30% more DMG)

A2- Transfers all debuffs on all other allies to this champion, and sets their timer for 1 turn. Grants this champion an extra turn. (6 turn cool down, books down to 3 turns)

A3- Exchanges all Debuffs on this champion, with all Buffs on one enemy champion, then sets their timers for 2 turns, this skill can be used while under any disabling debuffs. (6 turn cooldown, books down to 3 turn cooldown)

ASCENDED PASSIVE (Maybe a unique Aura)- All other champions of different names with KEEPER in their names, gain 10% to all stats when in the same party as this champion.

Ok, thats all I have for ideas for these 5 unique bosses as champions. Again this is just a fun idea I had, and felt like sharing. It is not meant to be pushed as an actual concept. Thank you for your time.