Slow them down, keep the beat.
ETB creatures, offering tempo-control and card advantage control the game vs. comers.
and destroy them.
Currently happy with matchups against delirium, zombies, marvel. UW flash is beatable. Control is a problem.
Cards
Creatures and artifacts, all good on their own, doubly good with Panharmonicon.
Removal
Reflector Mage,
Fairgrounds Warden
, Noxious Gearhulk, Skysovereign, Consul Flagship
Card Advantage
Glint-Nest Crane, Prophetic Prism, Thraben Inspector, Cloudblazer,
Restoration Gearsmith
. Honorary: Smuggler's Copter. Options: Gonti, Lord of Luxury, Filigree Familiar
Beats
verderous gearhulk
, Bristling Hydra.
Smuggler's Copter doesn't fit the deck theme, but it's very good.
Mana Fixing
AKA Why we can play 4 or 5 colors. Prophetic Prism, Servant of the Conduit. (Honorary: Aether Hub, Holdout Settlement)
Lifegain
Noxious Gearhulk, Cloudblazer, Authority of the Consuls. Options: Filigree Familiar, Arborback Stomper
Resilience
Eerie Interlude, Essence Flux help survive removal. Options: Bristling Hydra - very hard to kill with double energy resources.
Other Ideas
There's a ton of ways to exploit Panharmonicon. Here are other ideas not in this deck.
Fabricate gets doubled. Reckless Fireweaver gets nutty with double servos and double pain.
ETB energy gets doubled. Whirler Virtuoso can combo infinite with enough cards that trigger on creatures entering.
Saheeli Rai can copy a creature. Saheeli's Artistry copies two. Altered Ego can be a copy of anything you or they have.
Eldrazi can make double scions. Thoughknot Seer seizes 2 cards but only returns 1. With Displacer you can repeat these effects. This can even go infinite.
Eldritch Evolution can toolbox if not countered. Get a 5 drop on turn 4. Bring to Light is another toolbox.