Haha, great. He gonna be the Magnar of Thenn? I'm a fan of Gatiss's acting in The League of Gentlemen
and Nighty Night
. Also big on his Doctor Who novel Nightshade
. He's my ideal pick from the likely candidates as showrunner of Who when Moffat leaves.
When you're playing a starting wars that kill of tens or hundreds of thousands, that's an inherently risky business. I don't think inciting a Dothraki invasion is so much more risky than what's been done to the Seven Kingdoms in the inter-faction fighting, particularly in the Riverlands.
I think it's much easier to manipulate civilised factions as they have similar patterns of engagement. The Dothraki won't be beating drums and planning political strategies like Tywin or Roose, they'd just use feral brute force and tear a chunk out of Westeros.