Hydro-Channeler

Mana dorks that only pay for spells are a narrow tradition, and this is a Merfolk built entirely inside it. The first tap produces blue restricted to instants and sorceries; the second, for an extra mana, filters into any color under the same restriction. That fencing is what keeps the card from becoming a generic accelerant: it cannot ramp into a creature, cannot fuel an artifact, cannot help cast anything that stays on the battlefield. It exists to power spells and only spells, which pins it to one axis of deck rather than every deck that wants two-drop acceleration. The 1/3 body is the tell for how it wants to be used: it survives most early pings and blocks the ground while the spell count climbs, a defensive posture that matches a shell more interested in casting than attacking. The second ability is the more interesting half, because color-fixing tied to a spell restriction lets a two-color spellslinger reach a splash it could not otherwise afford without diluting its manabase toward creatures it will never cast. Where a classic ritual or accelerant asks what you can cast this turn, this asks a narrower question: what instant or sorcery you can cast, now or later, that the fixing unlocks. The rate is modest by design; the specificity is the point.