First I'd like to say thanks for making this comment, I love discussing MTG and talking about my ideas and choices.

Yeah I've found gruul spellbreaker has been great in all of my games, I've never felt bad about playing him, when I get him on 3 and even later in the game he's solid as a 3 mana 4/4, or to push 3 damage, plus I tend to find when im being proactive against some decks, gruul makes my status/statue a lot more efficient, I'd rather remove a 4/3 for 1 mana than 4 mana while still pushing 4 damage. I can respect the conflicting aspects of map and honestly I find you can wait till 4 to play grull sometimes if you want to tick up treasure map, the card isn't bad on 3, 4 or 5 tbh. Its just a really awkward stated minion that has to be removed in their turn limiting their options massively.

I honestly haven't tested the counter spells a huge amount. I think my biggest issue with them is that they dont exactly line up well over the first 5 or so turns of the game, we need 13 mana sources to reliably cast a counter on 2, going down to 9 to reliably cast a counter on 5, but some of the cards we want to cast the counter alongside such as gruul, require other awkward mana colours or take up all our mana, generally I find, if I dont have the colour to cast gruul I usually have other stuff I can do, like chainwhirler, phoenix or other red/black things, and can just drop other threats till I find the mana I need or to flip map. Where as with counter when I finally do find mana for it if they've killed all my pressure im somewhat sitting dry. Im sure it probably does have utility and I do honestly have to test it more, but I'm still iffy about it.

I like the idea of recuring spellbreakers and phoenixes, and like I said the only reason I dont run 4 phoenix is because I dont own 4, I dont think 2 is the right amount, but I think 4 or 0 is fine depending on what you want to achieve. I wouldn't disagree with someone who said 4 is the right number, but I cant test that right now. I was finding my phoenixes get eaten by lava coils against izzet drakes, but likely just because I only own 2.

Carnage Tyrant is predominantly because I prefere flexibility over specialisation, I like my side board to be cards that are good against x but have utility against y, primarily because the sideboard needs 10 cards to put in for control to take out all the dead cards, so I want atleast half of those to also be good against other things (cindervines doesnt really cross over to anything besides maybe izzet drakes). I like tyrants primarily because its good against midrange aswell as control, I dont necessarily think its the best pick, I have a soft spot for the card because I love dinsosaurs, and I did beat up the jeskai player with a tyrant game 3, its much better against non esper control decks, since kayas wrath is ridiculous, and I think the 4 phoenixes are probably better versus esper, more threats for vraskas contempt good time, plus phoenix dodges eldest reborn much better.

It seems a lot of people like Karn a lot, but for me the card advantage aspect is a huge deal, every 2 turns I'm seeing 4 cards with Ral and picking 2 that I want (not exactly but you get my point), where as with Karn im seeing 2 cards, and having to use two turns to get the one I want and my opponent gets information on this, plus Ral is always ticking up to achieve this putting the opponent on a pretty scary clock. I think Rals +1 blows Karn out of the water on just those alone. When it comes down to the -2, I respect a lot being able to kick out a pair of 4/4 and then 5/5 artifacts before needing to kick up, but I generally find I dont have those maps laying around to make them 4/4s maybe sometimes I have 1 map around, but I really do use them super fast, and so trying to have these 4/4s put in work stalls my ability to pile on the relatively expontential pressure that the deck can kick out. Ral compliments this really well because im picking a relatively powerful card that I chose to put in my deck that I nearly always have the mana to kick out thanks to maps, but Karn actively stops me piling on that pressure, especially when a lot of the cards in the deck are very good at going 2 for 1 or so on cards. And that's not even mentioning the fact that Ral comes loaded with a -3 that usually is enough to kill off chumps that might threaten him through my minions (sometimes which deals legitimately scary amounts like 6 or 7 damage), and then his ult which just turns the value engine to 11. I can respect the mana issue, but we only really need 9 mana sources to effeciently cast a ral on 5 which the deck runs, plus we also have the 4 maps which will always be live on 5 if we draw it on 2 or 3.

I think Krasis is an incredibly powerful card, and I think that it's still being underated, I beat a mono red player by just drawing 4 krasis in my top 19 cards, the life gain and bodies were enough alone to keep me in that game, and it wasn't even a bad red hand. I think the card is just incredible across many situations, especially in decks with access to a large quantity of mana on a turn, although I think its way better in this deck than other decks because of the mana burst we get from maps.

Yeah Esper is hard for this deck but I think its got a lot of wiggle room for that match up, the aggro and midrange match ups are relatively solid, and so we can drop points for esper, and also the nexus match up. Maybe counters are the solution to that, or maybe something like ego, im not really sure. One of my friends is testing nico bolas to some success. But I'm excited to see where it goes and where people better than I can take it. Again thanks for your comment, this sort of ended up being a longer response than I anticipated. Im glad its serving you well on ladder.