Do Seals add energy? Do Seals enter exhausted like units do?

No, Seals canʼt generate energy. They can be exhausted to produce 1 power of Sealʼs domain/color. Since you donʼt recycle them to make the power resource, you will be able to ready them and use them again on future turns.

Related: Rule 149.1, Rule 415.3.a, Seal of Discord, Seal of Focus, Seal of Insight, Seal of Rage, Seal of Strength, Seal of Unity