Minnea, Planar Tourist (MG01) [Unknown Event]

As Minnea, Planar Tourist enters the battlefield, choose a plane. Spells from the chosen planes cost {W}, {U}, {B}, {R}, or {G} less to cast. (They're from the chosen plane if it's clear beyond doubt from the name, art, flavor text, or whatever extensive research you've done and can show that they're from that plane.)