All the more so because you are seeing everything from the perspective of someone that you already know is doomed
Flein Sovereign doesnt have the insane upside of generating a wide board state like Arahbo, but giving you the opportunity to blow up artifacts or enchantments when you connect is surprisingly powerful in Pioneer

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You spend a lot of mana for a fog, but it can be worth it if you end up with a massive white creature especially if cards like Fling are a part of your plan
The edges are not perfectly sharp, possibly as a result of mass production