Shark tip then, you can use a single cutter shark for a one card combo to cheese out a utopic future dragon and place the seventh one on top of your deck (this takes up seven cards in your extra sadly but it’s still pretty powerful as far as sharks go)
Summon cutter shark and use its effect to summon a level 4 water.
Overlay them for bahumat shark
Detach one to summon number 71
Overlay rebarian shark for Full Armored Black Ray Lancer
Overlay black ray and bahumat shark for number F0 (xyz materials already on the monsters you used to overlay will be detached)
Use the rebarian shark to topdeck the seventh one
Overlay F0 for future dragon.