Nightmare
Lv3 mind + Lv1 dark
Ethereal
Cost: 10(?) mana
6 Life
0 armor
1 channeling - may not be necessary, would limit the sleep attack without it...
Legendary
Cantrip
Upkeep 3
As a move action it can teleport to a zone with a sleeping creature. (I thought this was cool - might be even more amazing and add to resiliency if it was a once a turn ready marker power)
Quick attack: Can cast sleep
Slow attack 1: Can cast mass sleep (enemy and friendly creatures)
Can stack sleep tokens (remove 1 per attack on a sleeping creature)
Each upkeep phase every sleeping creature within 1 zone from nightmare takes 1 direct damage for each sleep token it has, then heal nightmare the same amount.
Slow attack 2 (nightmare's blast): range 0-2, 1+x dice, dark, etheral, X = sleeping creatures within 1 zone of the Nightmare.
The vampiric effect may be a little unnecessary as its a cantrip and 6 damage is a pretty easy kill, it might make more sense for it to just get recast... so keep the mana in the 10 range, but leave it as a little fragile.
Mass sleep might be too powerful combined with the blast, but I wasnt sure if a single sleep was sufficient?
The creature still has quite a lot of flex, but against a solo buffed mage has little it can do, so isnt a guaranteed play.
so...
with a non-psychic attack:
Nightmare blaster
3 mind + 1 dark
cost of 15 mana
incorporeal, 10 life
attack 1 (sleep): psychic, unavoidable, target non-mage, 0 dice, 5+: put 1 sleep counter on the target
attack 2 (nightmare's blast): range 0-2, 5 dices, etheral, to cast this attack the Nightmare blaster must be in the same zone as a sleeping creature