Gorex's first ability can't reduce its cost below . You can exile any number of creature cards from your graveyard, even if they won't reduce Gorex's cost any further.

Include any additional costs to cast Gorex before applying its own cost reduction. For example, if Gorex is your commander and an additional cost of applies from the "commander tax," you may cast Gorex by exiling four creature cards from your graveyard and paying .