Regalia of Forsaken Blight(I am thinking they can add this into the adan reputation or a special item brought from merchant.)
Lv. 22 (50-60 reals) grey
Stamina- 20
Intuition- 20
Will- 20
• FOR ALL LEVELS: Allows the wearer to inflict the Heat of Blight on the user once a week which lends to the Madness of Blight but eventually goes to the End of Blight. (Item must be worn to activate and use the effect, once effect is used the equipped item can’t be removed.)
[Costs 1g to repair with a condition of twenty.]
Lv. 29 (upgrade cost is 60 sparks of abyss) green
Stamina- 24
Intuition- 24
Will- 24
Additional Abilities while inflicted with Heat of Blight, Madness of Blight, or End of Blight:
• Seal of Blight I ability is passively cast on monsters that the wearer summons into the battle.
[Costs 2g to repair with a condition of twenty-two.]
Lv. 36 (upgrade 120 spark of abyss) blue
Stamina- 28
Intuition- 28
Will- 28
Improved Abilities while inflicted with Heat of Blight, Madness of Blight, or End of Blight:
• Seal of Blight II ability is passively cast on monsters that the wearer summons into the battle.
[Costs 2.4g to repair with a condition of twenty-four.]
Lv.44 (upgrade 180 sparks of abyss.) purple
Stamina- 32
Intuition- 32
Will- 32
Improved Abilities while inflicted with Heat of Blight, Madness of Blight, or End of Blight:
• Seal of Blight III ability is passively cast on monsters that the wearer summons into the battle.

[Costs 2.7g to repair with a condition of twenty-six.)
Lv. 51 (upgrade cost 240 spark of abyss.) orange
Stamina- 36
Intuition- 36
Will- 36
Abilities while inflicted with Heat of Blight, Madness of Blight, or End of Blight:
• Seal of Blight III ability is passively cast on monsters that the wearer summons into the battle.
Additional Abilities while inflicted with Heat of Blight, Madness of Blight, or End of Blight:
• Cry of Blight ability is passively cast on the wearer which increases stamina.
[Costs 3g to repair with a condition of twenty-eight.]
Lv.67 (upgrade cost 300 sparks of the abyss.) red
Stamina- 40
Intuition- 40
Will- 40
Abilities while inflicted with Heat of Blight, Madness of Blight, and End of Blight.
• Seal of Blight III ability is passively cast on monsters that the wearer summons into the battle.
• Cry of Blight ability is passively cast on the wearer which increases stamina.
Additional abilities while inflicted with Heat of Blight, Madness of Blight, and End of Blight:

• Berserk Rage which has a small chance of dealing 240% damage, but this attack will leave the user disoriented for two following rounds.
• Defiller Priest which provide a reskin of the defiller original look into a even more menacing look while also providing other players in the battle that are fighting with the defiller an option to get the Heat of Blight (for this combat only)and providing them with Cry of blight ability(for this combat only). [Maybe could happen or at least the reskin.]
[Costs 4g to repair with a condition of thirty.]

Counterarguments:
Too overpowered: The defiller boost is roughly 15% hp and 15% damage boost in its first stage while providing a 30% boost in the second stages, a player with a solid dragon can in most cases defeat the defiller player very easily. Also note the defiller player in the second stages get a lot of serious restrictions.
Too many Cons: The defiller boost only get the serious cons when on the second stage with the better boost, but if your plan out the first stage well and prep a bit for it the second stage could be beneficial aka sea battle, ruins, clan wars, and etc that your mind can come up with.
Extremely lacking compared to Neph: neph hp boost is dependent on gear from what I been told though unsure if the base form itself gives hp though if it does its lacking but the damage yes it outclasses the defiller by a high margin, but I will ask you this unlike neph the defiler form is constant so no waiting is involved and doing enough damage early on could help win the fight.
Seal of blight sounds like your avoiding the dragon restriction: The answer to this quest is yes/no because no sketelar or monster idol can replace a dragon even with a 2x times max damage boost since they usually only have one ability and much less hp then a dragon.
The Regalia is Pricey: It turns you into a defiller with a bit extra abilities enough said. :P
People will just buy this instead of even bothering getting neph: if you think defiller can replace neph lol not in your dreams, the amount of damage a neph can do plus the fact they have much higher stats in all areas make defiller look pretty weak actually the only advantage defiller has with this regalia mind you is the improved mob summon strengths and that it is constant.
Turning other people to defillers is broken/or will make them hate you: To the point that its broken its doubtful since most people will prefer there dragons over it but if they do chose to it will likely be because the dragons they have isn’t that good. People won’t hate because its optional like how the resurrection is optional once you die and have dragon out or requesting if you want to leave combat.