Boss level 50 health per tier.
Lvl 5-25 has approximately 950k Health
Lvl 26-50 has approximately 2.9 Million Health
Lvl 51-75 has approximately 7.2 Million Health
Lvl 76-100 has approximately 11.5 Million Health
Lvl 101-150 has approximately 18.5 Million Health
Lvl 151-200 has approximately 38 Million Health
This information has been 'borrowed' (not stolen) from a Modern War thread. The boss health appears to be similar to Kingdom Age and for that reason I believe the figures may be the same. Please let me know if you know otherwise and I will update the table.
Collect all 9 units
Collect all 9 units and receive the Umbral Knight 12,158 / 6,546
Defeat the Soul Sucker multiple times to receive prizes
Defeat the Soul Sucker 5 times to receive - Talus Creature 212 / 307
Defeat the Soul Sucker 10 times to receive - Cursed Soul 344 / 282
Defeat the Soul Sucker 15 times to receive - Decrepit Treant 575 / 309
Defeat the Soul Sucker 20 times to receive - Talus Archer 529 / 764
Defeat the Soul Sucker 25 times to receive - Greater Lich 858 / 702
Defeat the Soul Sucker 30 times to receive - Underworld Lord 1,474 / 793
Defeat the Soul Sucker 35 times to receive - Talus Lord 1,287 / 1,858
Defeat the Soul Sucker 40 times to receive - Fallen Drake 2,572 / 2,104
Defeat the Soul Sucker 45 times to receive - Cadaverous Wendigo 5,319 / 2,864
Defeat the Soul Sucker 50 times to receive - Soul Sucker 15,197 / 8,183
Information kindly provided by l3lade2 of Murder of Crows
With help of your guild defeat the Soul Sucker multiple times to receive prizes
Defeat the Soul Sucker 5 times to receive - Revenant Servant 223 / 322
Defeat the Soul Sucker 10 times to receive - Arachnid Thrall 379 / 310
Defeat the Soul Sucker 20 times to receive - Umbral Wight 661 / 356
Defeat the Soul Sucker 30 times to receive - Raging Bull Ogre 635 / 917
Defeat the Soul Sucker 50 times to receive - Fell Drider 1,073 / 878
Defeat the Soul Sucker 75 times to receive - Vampiric Servant 1,916 / 1,031
Defeat the Soul Sucker 100 times to receive - Undead Scourge 1,737 / 2,509
Defeat the Soul Sucker 200 times to receive - Wolf Changling 3,601 / 2,946
Defeat the Soul Sucker 300 times to receive - Tartaraun Mage 7,713 / 4,153
Defeat the Soul Sucker 600 times to receive - Knight of the Undead 22,796 / 12,275
Guilds that have completed the guild quest in approximate order
FORUM UNITED NATION
Samurai Blood
The Assassins Guild
Order of Dragon Knights
Black Grypons Knights
Supreme Kingdom
Murder of Crows
FUA II
The Fighting Squirrels
Alderaanian Knights
Spectral Agony
Knights of Singapore
Strength and Honor
The dark knights
Sir Vyper
The Sailor Scouts
Starks of Winterfell
Justice from blood
Power fighters
Red Dogs
The Peoples Front of Judea
sir SMP
Kingdom Age Guild