My circle has been playing a fair bit of Domination recently, and not one of us has ever used, nor can see a time when it would be useful to use, the V'Torrak tile.
Our consensus is basically that it is not worth sacrificing a V'tar point unless you are already gaining more each turn than your opponents, and even if you are, you will almost certainly have better things to do with 7 mana rather than summon a Sslak with it.
Are we missing something here? The Domination rulebook seems to think that the V'Torrak is a great thing, very useful, but we can't see it.
Has anyone used the V'Torrak? Under what circumstances would it be worth giving up 10% of your victory points and a large chunk of your round's channelling, to summon a Sslak?