Clues were awesome in Shadows Over Innistrad, and Ixalan had the Merfolk deck, but on the whole, card draw and ramp are more of a general style of Magic, not a defined synergy
#10 Alhammarrets Archive Alhammarrets Archive is also intended for lifegain decks, although you could run it in a deck that benefits from drawing cards on your opponents turns
As a bonus, Enduring Vitality itself can chump block in combat, die to a board wipe effect, or even be sacrificed without losing its effect, since it comes back as an enchantment
This would allow us to design many different cards with different outputs that represented everything waterbending could do, which would be tied together by a shared, flavorful input
So, while it is tempting to just look at the cards that will make Delirium and Rendmaw, Creaking NestRendmaw, Creaking Nest go, I think we'll be better served by getting a snap-shot of all the options that will get your type-count up, in the graveyard or otherwise
Of note, the buyback spells Allay and Shattering Pulse cost five mana to cast with buyback, which is exactly what Sonic Rainboom provides