This a big mana deck all about Mystic Forge and Karn, the Great Creator. The gameplan is rather simple - you mainly play Astral Cornucopia and Everflowing Chalice for zero mana, then charge them up with Coretapper and Surge Node. At this point, there will be more than enough mana for making Urza's Saga tokens or slamming a Karn.
Karn, Scion of Urza and Karn, the Great Creator are both very very good. Karn, the Great Creator pulls win conditions or strong answers to the opponent out of your board. Jester's Cap is very important so you can deal with Stony Silence or Shatterstorm before they ruin your day. Karn, the Great Creator can also turn cards like Spine of Ish Sah into big creatures. Karn, Scion of Urza is good too because it creates massive constructs and can also dig for key cards like Mystic Forge.
Speaking of which, Mystic Forge will end the game if you have the mana. It doesn't take much, just a Voltaic Key with any mana rock that has charges will be an unstoppable amount of value. Throw in a Firemind Vessel or two and the game is probably done! Just play a Walking Ballista that is too big to deal with or something. If the opponent plays a lot of removal and can deal with it plus the giant constructs from Urza's Saga, then just get Orochi Hatchery with Karn, the Great Creator and make more tokens than can ever be dealt with. Manifold Key can also make things unblockable if that is something that is needed.
Finally, more than just Urza's Saga is great for the lands. Blast Zone can kill things, Radiant Fountain will keep you alive against burn/aggro matchups, and Zhalfirin Void will make our draws better and manipulate the top card of the library to further enable Mystic Forge.
The only issue with the deck is that if Urza's Saga is ever banned from modern, then the deck dies. Urza's saga is so insane because it can assemble every part of the mana engine. It can get Everflowing Chalice, Manifold Key, OR Surge Node. It is just an insane card!
