Artefacto
Si fueras a perder maná no usado, en vez de eso, ese maná se convierte en incoloro.
As long as Horizon Stone remains under your control, you'll retain unspent mana as steps and phases end, although that mana will become colorless. This means you can add mana and spend it during a future step, phase, or turn. Once Horizon Stone leaves your control, you'll have until the end of the current step or phase to spend the mana before it is lost.