Cards with X in their casting cost are generally quite good with Vial Smasher, as their converted mana cost is the total amount you pay for it while you cast the spell (note that this only applies when you cast it. For example: CMC of a Chalice of the Void in your hand is 0, but when you cast it for X=1, its converted mana cost would be counted as 2 for Vial Smashers trigger, because you paid 2 mana). These three are quite powerfull with Vial Smasher: Exsanguinate, Torment of Hailfire and Debt to the Deathless.
One other card I really like is Dictate of the Twin Gods. You can flash it in on the opponents end step for 5 dmg and then double up the damage of your next spell in your turn. Its devastating when combined with extra turn effects.
December 14, 2018 11:18 a.m.
Sorry for the suggestions that are already in your deck btw, got a bit carried away ;)
One more thing, I think Sunhome, Fortress of the Legion is a great way to make Ishaj a real threat without investing too much resources on a voltron strategy.