Creatures you control have haste.
Cascade, cascade (When you cast this spell, exile cards from the top of your library until you exile a nonland card that costs less. You may cast it without paying its mana cost. Put the exiled cards on the bottom in a random order. Then do it again.)
Each instance of cascade triggers and resolves separately. The spell you cast due to the first cascade ability will go on the stack on top of the second cascade ability. That spell will resolve before you exile cards for the second cascade ability.
10 Nov 2020
Maelstrom Wanderer gives itself haste.
10 Nov 2020
No matter what spell you cast with the first cascade trigger (or with any cascade triggers that result from casting that spell), the second cascade trigger will look for a spell with mana value less than Maelstrom Wanderer's mana value of 8.