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Collision of the Realms is a relatively light chaos effect compared to something like Warp World, but it could still get a few groans from the table
Wight of the Reliquary Knight of the Reliquarys morbid counterpart sacrifices creatures instead of sacrificing lands, which is honestly way better with all the same potential upsides
Sure, the deck has weaknesses: cheap creature removal cards like Go For The Throat, bad opening hands, or simply just not getting enough land
Rise of the Floodborn is already shaking things up - though the current frontrunner appears to be an Amber/Emerald Discard deck, so any deck playing Hiram Flaversham will have some stiff competition
The First Sliver and Sisay, Weatherlight Captain are assuredly more powerful cards, but they're fairly interchangable with other five-color legends in their respective archetypes