The First Partner Illustration Collection celebrates Pokmon's 30th anniversary by spotlighting the franchise's iconic starter Pokmon as Illustration Rare-style promo cards the kind of artwork-forward cards that collectors specifically hunt
Stormchaser's Talent is one such Class: If it exits and then returns to play, you'll get a second 1/1 blue Otter token, and if it gained a level before being exiled it will be reset, and you'll be able to use the second ability to fetch an instant or sorcery from your graveyard a second time
Converting bodies to mana is the most direct way of doing this with the cards listed in the OP or these: As the OP noted, Convoke has this built into the mechanic: You can support these effects with creatures that add mana in another way at the same time: Some of my favourite lands let you use creatures to enable messed up stuff: You want creatures as potential mana sources that are also mana sinks: Once you have lots of creatures lying around you want ways to pump them - ideally scalable and/or attached to creatures themselves: Here's an example list with a tribal focus: Absolutely love decks like this #36 Oh, hey, look, it's basically Wilderness Reclamation
Even better, his powerful [Trigger] allows you to play him for free from life by trashing a card, giving you an immediate reactive board presence or a surprise blocker when your opponent least expects it
