Synchro, of course, is useful for calling high rank X
(Handy tip: any card that says without paying its mana cost can cast a no-mana-cost card.) Finale of Promise, Dreadhorde Arcanist, Halo Forager, and Vadrok, Apex of Thunder will all copy Living End if it gets milled
You can also combine Notion Thief with something like Windfall in order to strip your opponents hands and draw a massive amount of cards
Sure, winning a casual event at your LGS is fun, but nothing beats the knowledge that my entry fee was already virtually covered by the cards I opened in my pool
Its attack is weak, unreliable, and heavily dependent on coin flips, while most Gyarados cards have not done enough to justify building around it
Keeping Hiram and an item like Pawpsicle can enable you to play a lot more aggressively and add more ink to your inkwell than you otherwise could