I think Nightmare Painter is just a fantastic card and should be a part of EVERY Phantom Blaster Overlord deck. Personally, i think running 2-3 is pretty good.
Obviously this card is a 6k boost at the very least, letting 10k RGs require a 10k guard against most vanguards. What this card also lets you do is place a Shadow Paladin from your hand into your soul.
Strategies and game play:
The main strategy that this card provides is putting PBD into soul early and allowing a faster ride for your 13k VG.
Ways to counteract it:
The best, and only way that i can think of, to counteract this card is to rush the opponent. if you make them guard, they might lose the chance to use this card.
Biggest Pro is getting a 13k VG by turn 3. if you go first, there is a good chance your opponent may even still be at 8-9k, making a good attack very easy to pull off.
Disadvantages of this card are mainly that boosting Blaster Dark - a very common G2 in a Phantom Blaster Overlord Deck- it will only hit 15k, which is pretty ineffective against 11 or 13k VGs.
A lot of clans have similar cards, Dream Painter for RP, etc
Artwork and aesthetics:
I love the artwork and i like the RP doppelganger
I give this card an 8 out of 10