MArcomage

my suggestion:
4. when token counter reaches 100, then zero Holy and Alliance enemy counters. Stock +N/20, where N=Amount of Holy and Alliance token subtracted from enemy counter. If no counters found then enemy stock -3

5. replace a Holy or Alliance card from enemy hand randomly with Purified Ashes.

6. discard all Purified Ashes cards in hand and replace them with non-rare Undead cards. Discard all Searing Fire cards from hand and replace them with non-rare Demon cards

Maybe i need to add a special effect on the third effect to gain a Hell's Portal. But i thought that it would be more like the dragon keyword ^^.

my version:

Basic Gain: 11, Bonus Gain: 3, Side-Effect (Hell's Army): replases up to 3 common (may be uncommon) cards to Deamon warrior.

Necropost! (this would be a nice name for a card)
I've created some Demon concepts thus I revived this thread to find a good power for the keyword.

I like this Lord Earthfire's suggestion:

Basic Gain: 16, Bonus Gain: 4, Side-Effect (Mana-Flames): Convert an amount of Enemy Gems equal to the Rarity of last played Card (C: 2, U: 4, R:7) into attack.

Cards that could gain Demon:
Abyssal scavenger
Curse
Daemon
Devil
Devilkin
Imp
Risen angel
Succubus

Another possible bonus effect:

Basic Gain: 10, Bonus Gain: 5, Side-Effect (Eternal damnation): Tower: -N, Enemy Tower: -N N based on played card's rarity (C: 2, U: 5, R:10). Can't lower tower below 20, can't lower enemy tower below 10.

Lord_Earthfire wrote:

3.
If you got a "Hell's Portal" in your Hand while playing a Demon Card, and if #Gems>13, replace one "Hell's Portal" on your Hand with a Demon Card of the Higher Rarity and reduce your Gems by 13.
If last Card played while triggering this effect is rare:
Gems: +33

I think this is a truly unique and awesome suggestion. I think it may need a little tweaking though:

When triggered, the next card will be a demon of equal or greater rarity. Gain 1/3 of the cost of the summoned card.

I think this has a feel of bringing a demon through a portal as part of an onslaught, but there's a chance that you get very little resources.

Other cards that could have Demon:

sacrifice, soul sacrifice and dark ritual.

The damage on enemy tower I have proposed is too harsh. I change the proposed bonus:

Basic Gain: 10, Bonus Gain: 5, Side-Effect (Eternal damnation): Tower: -N, opponent suffers N damages
N based on played card's rarity (C: 2, U: 5, R:10). Can't lower tower below 20.

I think you should raise bonus damage to 2N. Now it's self-crippling Beast.

Do not have the time to follow forum or play - but here's an idea (probably suggested before)

Make holy token affect demons as undead.

I liked the tower damage; it fits with the "feel" of the keyword. My only concerns with it are 1) boosting the already powerful tower- decks and 2) I don't like the "can't lower below X" part: It feels too safe, for want of a better word. I don't feel the demonic forces would choose not to take their toll on you just because you are weak.
Maybe you could have the limitation only on enemy tower? For example:
Tower -X, enemy tower -Y (can't lower below Z)