Originally Posted by
Speedbump
Haven't tested Swiftspear enough to make a claim for the Miracles side, although it feels like having another creature that gets hit by Terminus, Swords to Plowshares, and Counterbalance isn't the greatest card to have in that match-up. It might just be useful as Goblin Guide 5-8, as another creature to go underneath the Counterbalance soft-lock/hard-lock.
I feel that in metagames where Swiftspear would shine in, would typically be an environment in which Burn is a pretty mediocre metagame choice. If it's the best deck you have for that metagame, then still run it, although it is advised to switch to UR Delver if you still want to play an aggressive deck with Price of Progress+Swiftspear.
My list of core cards is as follows:
8 Fetchlands
8 Mountain
4 Goblin Guide
4 Eidolon of the Great Revel
1 Sensei's Divining Top
4 Lightning Bolt
4 Chain Lightning
4 Lava Spike
4 Rift Bolt
4 Price of Progress
4 Fireblast
2 Sulfuric Vortex
This leaves 9 spots for metagame choices, of which 2-4 are lands.