Maybe Mindbreak Trap over Summary Dismissal, I know it doesn't counter abilitys, but it can be cheaper and it doesn't have to counter your spells too.

Flooremoji I guess my thought with Summary Dismissal is that it's good vs Tron, Eldrazi, Storm, Humans, Planeswalker abilities, decks that rely on ETB and trigger effects, anything that can't typically be countered (since it's exiled), and now Jund/any deck playing Bloodbraid Elf. I've actually considered running 4 in the side. But I have been meaning to do some testing with Mindbreak Trap

I believe the reason a lot of people are saying Mindbreak Trap (aside from the fact that it costs 0 mana eventually), is that double blue tends to be a little difficult for blue tron. You run 8 sources, and I'm sure you've been in the situation of holding cards back just to counter something because you have to choose between the two. Mindbreak Trap allows you to stop something for free, AND hold up counters, or cast for free if needed. I completely understand that Summary Dismissal is better overall for stopping Emrakul, the Aeons Torn because it will also stop the extra turn trigger. However, Mindbreak Trap tends to be better in the meta we're in with Gifts Storm running about. Not to mention, a free counter if you get into a counter war with another control player.

I noticed something that wasn't in your sideboard, Trickbind. You seem to be worried about so many triggered abilities, so here is a card you should look into and playtest. I know that adding in both is more slots, but since you're considered 4 Summary Dismissals maybe do a split of 2/2 here. That's what I have in my deck. Trickbind hits ALL of the same cards that Summary Dismissal can hit, except of course Emrakul, the Aeons Torn which will resolve, but your opponent won't get another turn. If Emrakul, the Aeons Torn is truly that prevalent and is constantly cast that much in your meta, by all means keep Summary Dismissal, but some food for thought. I just wanted to lay out some reasons as to why people keep recommending one card over what you're playing. Of course, above all, play with what you like. It is more important.

Pheardemons you make good points. I'm grateful for the feedback, that's what I'm hoping to get out of this deck list. Suggestions, criticism, and dialog. I'd really like to do some testing. Just hard to drop $10 per card on something you are unsure of and none of the big names in U Tron play Mindbreak Trap. I have some tourney store credit winnings I might put towards em.

I understand that as well. There is a solid 20 price difference between the two. U-tron plays counters which is why some people don't care for Mindbreak Trap. However, since you're playing a card that is similar, maybe it is worth it. I'm only mentioning it because you're playing a similar card, plus, gift's storm is everywhere. At least in my meta. It's a card that can definitely destroy them by making them combo out, then you stop all of the spells, at that point you can just sit and wait until you draw what you need because essentially they're out of gas.

Those are just the thoughts and suggestions. If big names don't play it, there is definitely a reason behind that. Again though, if Summary Dismissal has worked for you, you don't need to fix it when it isn't broken.

Pheardemons just blew out an Emrakul, the Aeons Torn with Summary Dismissal way satisfying!

I will take the advice to heart. There is an eggs player and a through the breach player in my meta. So it might be worth trying.

If you want to counter aggro decks, put in Willbreaker along with Sleep or Archetype of Imagination, which will instantly all of the opponent's creatures with "creatures opponents contrpl lose flying and can't have or gain flying" triggers willbreaker and you get all of their creatures

Iron_eye2 unfortunately, they are all a little too slow. for something not instant speed just won't cut it. But I have good options like Silent Arbiter and Chalice of the Void for aggro decks.

Iron_eye2 - I just want to let you know those interactions don't work the way you are wording them. Sleep targets the player, not the creatures. Archetype of Imagination doesn't target any creatures at all. Those are "world" effects that affect the board, but do not specifically target. You'd want an effect like Jace, Telepath Unbound where his uptick will give you whatever creature, or something like Caller of Gales. Anything that is consistent and actually targets.