Comps and promo codes
Give tickets away to sponsors, cast and crew, or volunteers, and take something off with a code buyers type at checkout.
Comps
From a show's More, Give comps: who they're for, how many, and why (a sponsor, cast and crew, a volunteer, or another reason). They take places like sold tickets, and show among the show's orders.

Promo codes
Go to Settings, then Promo codes, and add one: the code buyers type, a percentage or an amount off, and if you like its last day and how many times it can be used. Under Shows, tick the shows it's for; it isn't for tickets unless you pick some. Under For, the classes it's for: none picked, it's for every class.

At checkout, buyers tap Have a code? and type it, in any case, and it comes off each ticket for those shows.