Thanks for this great post. I've not played much with these promo cards so this was a very interesting read for me, learning about their strengths.

My brain started working on possible other uses for Rune Arcanist, and I landed on the following combo: Nidhoggr+Redwyrm Dragon+Rune Arcanist (with the +2 speed, execute tactic). Disregarding other buffs, the Dragon has a base speed of 8, flying, and gets phase. Sounds like fun!