The magic screen is pretty basic. It allows you to select the dominion you are targeting, if you are casting an offensive spell. Success is based on your wizard to land ratio, versus your target's wizard to land ratio. Below that is a simple dropdown menu where you select the spell you wish to cast. The cost of each spell is listed next to the spell. That cost increases relative to the size of your Dominion. Spells cost mana and magic strength. Magic strength reaches 100%, and so long as your magic strength is above 30%, you can cast spells. However, the weaker your magic strength is, the more succeptible to magic you are. Every spell you cast reduces your magic strength, and it automatically repleneshes a bit every hour. Also, magic operations do more damage if you are at war with the opposing Dominion's realm. Some spells can only be cast if you are at war with the target's realm, or if the target attacked you in the past 24 hours. These spells include Fireball, Earthquake, Lightning Bolt and Disband Spies. Damaging spells cannot be cast until the 7th day into the round. For more information on spells, please take a look at The Operations. You can also train ArchMages from existing wizards (not draftees). ArchMages cannot be assassinated, and count as two wizards, instead of one.
Information gathering spells will be posted to your realm's Op Center. You have the option to delay the posting of this information to your op center if you so choose. A menu here gives you the option to post this information immediately, wait 15 minutes, or wait an hour. By posting information to your Op Center, you and your realmmates can help one another find targets and aid each other when a realmmate is unable to get information they need.