There's a smattering of cards that specifically interact with otters or make otters, and many of them are nice, efficient cards, even for a spellslinger deck with inexplicably few otters: Lilypad Village Valley Floodcaller Harnesser of Storms Otterball Antics Pearl of Wisdom Rockface Village Splash Portal Stormchaser's Talent Valley Flamecaller All of this adds up to an Izzet Prowess deck that features otters, which is awesome
Sacrificing your own creatures is, as already underlined, a big point in the deck, seven creatures target it
Hollow One and Vengevine might not be the best version of this archetype but its where I want to start
When you do, return Calim from your graveyard to the battlefield tapped
At first, you only have Character and Action cards to understand, with these being fairly easy to grasp