Here's the planechase deck my playgroup uses. Let me know if you have ideas to make it more ballanced (we all use all sorts of different decks, and we didn't want to break too many of them...)
The cards that there are two of are ones that cause the most chaos, and are the least deck-breaking. The cards that there are one of are either 1) cards that we don't care too much for, but are still nice to have on occasion, or 2) are cards that breaks ONE of our decks, and so we allow it, because it won't be too bad all the time.
Got any creatureless control decks? The Hippodrome gives you much joy! Alternatively, Sanctum of Serra can play nice with control as well.
I'm glad to see you shied away from Lethe Lake and Naar Isle. Those can suck the fun from a 4 or less player free for all.
2x Morphic Tide
2x Mutual Epiphany
2x Interplanar Tunnel
2x Time Distortion
1x Reality Shaping
1x Spatial Merging
1x Chaotic Æther
Planes (25)
2x Trail of the Mage-Rings
2x Horizon Boughs
2x Quicksilver Sea
2x Windriddle Palaces
1x Orochi Colony
1x Truga Jungle
1x Bloodhill Bastion
1x Talon Gates
1x Lair of the Ashen Idol
1x Zephyr Maze
1x Furnace Layer
1x Takenuma
1x Hedron Fields
1x Stensia
1x Selesnya Loft Gardens
1x Mount Keralia
1x Gavony
1x Karasha Foothills
1x Edge of Malacol
1x Norn's Dominion
1x Grove of the Dreampods
The cards that there are two of are ones that cause the most chaos, and are the least deck-breaking. The cards that there are one of are either 1) cards that we don't care too much for, but are still nice to have on occasion, or 2) are cards that breaks ONE of our decks, and so we allow it, because it won't be too bad all the time.
I'm glad to see you shied away from Lethe Lake and Naar Isle. Those can suck the fun from a 4 or less player free for all.