card proxy mtg Custom - Chains of Mephistopheles You may cast the copy without paying its mana cost Proxy Guide – Bazaar of

For instance, the herbturn draught "transforms the imbiber into something verdant and plantlike", which might mean having your skin turning into armored bark, having your hair turn into photosynthetic leaves, turning you into an immoble and voiceless tree but also purging you of all curses and diseases up to and including lycanthropy once the transformation wears off, turning you into a dryad, turning you into a living dandelion seed that blows away on the wind, covering you in thorns, or turning your arm into a branch that grows a delicious healing fruit

If it's something you can spend mana on, it's a cost

That said, its probably seeing play only in Commander, unless you do some crazy Omniscience shenanigans in formats like Standard

Gaea's Blessing - Stops you from being milled, but it's real purpose is to bring back Elixir of Immortality if it got removed