In addition to blue backings, some first edition Topsun cards lacked a set number
This can come in useful if your opponent has an Ability that stops you from evolving, attacking, or using your own Abilities
Lugia V
Aside from that, the following cards mention oozes in their rules text, including a few token generators: Convert to Slime Gelatinous Genesis Corrupted Zendikon Gutter Grime March of the World Ooze Miming Slime Mystic Genesis Ooze Flux Ooze Garden Slime Against Humanity Slime Molding Gutter Grime is a strong enchantment for a typal build, but Slime Against Humanity is fun since it lets you break deckbuilding rules
Well, mana spells are half the equation of a Storm deck, with the other half being card draw, which our commander transforms burn spells into
This manifests in the Magic set with the return of the Lesson spell subtype from Strixhaven: School of Mages