I like this idea alot. Horizon Chimera seems like a really solid card after reading him a second time. I'm not sure how I like a few specific cards but I'm sure you had your reasons for each. I will say that 22 lands seems like it's a little low and that Prophet of Kruphix seems like it should be main boarded. I'm currently playtesting it now at 2 and it just screams amazing. Having all your mana and creatures untap on their turn with a counter spell in hand or a creature to flash is just insane. Also I'm not sure how well Chronicler of Heroes fits this deck. Essentially it says pay three mana and draw a singular card but only if a counter is somewhere on a creature you control. I think it would make more sense to possibly play Loxodon Smiter in that spot. Solid uncounterable drop that can be ramped into and be a brick wall as you set up your combo. Daxos seems a little situational and I think I like Syncopate more so than Swan Song since it deals with everything and you aren't giving them a chump blocker with evasion but that's just my opinion. Also no Sphinx's Revelation ? Even so, all around great idea. Take my +1 sir!

Sadly, I don't own any sphinx ): I gave them to a friend.

The only reason I mainboarded Chronicler of Heroes is because if it enters the field with a Fathom Mage , i will draw two cards, it was better when i had Gyre Sage too.You made me realise I could use those 4 slots for a better card

I will need a lot of testing for this deck.

I appreciate the feedback, thx!

I built something similar, only used Voice of Resurgence instead of Fleecemane Lion . I was eaten up by control decks. What are some good sideboard ideas? I was able to get a turn 4 infinite combo going in one game!