Main purpose is to clear the board to manually activate Triangle's GY effect, and it allows Bystials to be used as material. Not only is summoning 2 bodies for free broken (1 of which is Anemone, so the GY eff is basically a 1 card Link-4), but it also puts Triangle in banishment, giving us a high link rating to summon via Bubble Reef.

Take for example any 1-card starter (Tang, Springirl, Trickstar, or Sea Horse) that makes a link-4 on their own. Going second, if a Bystial is on the field the prior turn, all we need to do is make Triangle at the very least, and hold on to the Dive we searched with Sea Angel for now. Link the Triangle and Bystial into Lizardose, clear the board while drawing 1, activate Triangle's GY eff, link climb into Marble, add a monster to prepare for Reef pitch, use Dive to bring out the last body needed for a link-4, link those into Reef, bring back Triangle into Zone 2 or 4, link Reef into Zealantis in the zone above Triangle. That's the very basic concept of the second part of my notes.

So now we just turned a Bystial (or other Marincess extender) and a 1-card Link-4 into Co-linked Zeal, live Wave, and card advantage from the extra draw. Still in MP1, we can proceed to battle, destroy at most 2 back row since Zeal and Triangle are co-linked, and if need be, go into MP2 and non-target banish everything that isn't Water. Hopefully we don't need to activate Zeal's banish eff since that means we lose the co-link. Usually it's more than enough to win the grind game we caused.