@Waikiki: I think using Selkie against Merfolk might be good but only if you don't cut Path to Exile from the board because you will still need the additional removal. That said, the Selkie might actually be better than Survival because it does the same as Survival but quicker: provide CA. I'm more sceptical against CB-based decks. In case of the usual CB Bant it might be worth it because their threats match ours while we got protection from StP via Spellstutter Sprite. Not to mention broken openings of Hierarch into turn 2 Selkie drawing 2 additional cards on turn 3. But giving up what makes our lategame better than theirs, namely Survival? I feel at least uncomfortable with that. Especially against strategies that just dominate us without Survival (read: Natural Order).
Oh, and of course one has to sacrifice his graveyardremoval in the process. Generally speaking there are four kinds of sb cards:
- Anti Combo (MM, Spell Pierce, Canoninst, Teeg...)
- Anti Control (Krosan Grip, Kira, Llawan...Selkie?)
- Anti Creature (Path, Jitte, additional RWM...)
- Anti Graveyard (Faerie Macabree, Crypt, Relic, Grunt...)
Looking back at all the sideboards I played so far it was usually only possible to play enough cards in 3 of these 4 categories. So far I would recommend this for an unknown meta:
(playing 3 SSS and 3 Daze maindeck...giving Daze a try right now)
3x Pierce
1x Canonist
3x Grip
1x Kira
1x Llawan
3x Path
3x Faerie Macabre
Of course one will rarely play in an unknown meta. For example, when I play in southern Germany I'd definitly run the 4th Krosan Grip instead of a Faerie because Dreadstill is #1 DtB over here. I'd really like to try the Selkies, maybe I'll just cut down on 1 Grip (going back to 3) and 2 Faeries to try 3 Selkies. Still, I have doubts about boarding out Survival here, but I guess one can easily replace 3 Daze against CB.
By the way, did I mention why Ethersworn Canonist is good in matchups where you assume the control role? Against storm combo it's quite obvious but especially against Reanimator, dropping Canonist stops them from using Force of Will to back up their combo while you can easily just Force/Spellstutter their Reanimate/Exhume.