Run Spell Snare instead of Spreading Seas

I might run Spell Snare in the sideboard, but I don't know that I need it mainboard. I already have answers for the vast majority of things that Spell Snare would counter mainboard, and they are all far more versatile.

Things like Path to Exile , Lightning Bolt , Electrolyze , Izzet Charm , etc.

dude, Modern is littered with 2 drops. Everything from Tarmogoyf , which a lightning bolt is generally never going to be able to deal with, to a Mana Leak or Rune Snag and you only have to keep 1 open for it. the only card you mentioned above that is better is Path to Exile but that's simply because that's the best removal card in the game. You also have way too many lands and planeswalkers. You only want around 22 lands when playing Delver of Secrets  ^Flip . He wants to flip and running fewer lands and extra spells like Serum Visions allows for that to happen. You need Serum Visions over anything else really.

I don't run Delver of Secrets  ^Flip in this deck.

And I have spent hours debating whether or not Spell Snare is good enough to see significant mainboard play anymore, and the inevitable conclusion I have reached is no. 1 or 2? Sure if you don't have many other answers to their two drops. Any more than that is a dead slot that could easily be something much more versatile.

It may just be me, but I personally find Render Silent better against combo, at least when we aren't talking about a U vs U matchup.

i want this deck...

This looks like a solid example of R/W/U midrange and a total pain in the ass to play against.

how does the mainboard Thundermaw Hellkite work for you?

Very well actually. It finishes out games really efficiently, and by the time he comes out they tend to have exhausted their removal on Snapcaster Mage and Vendilion Clique .