You should watch:

Unification: Part 2

This was episode number 8 of season 5.

The following characters appeared in this episode:

(as William Bastiani)Omag

(uncredited)Romulan Guard

(as Harriet Leider) Amarie

(uncredited) Omag's Woman

Captain K'Vada

Captain Jean-Luc Picard

Counselor Deanna Troi

Commander Wiliam T Riker

D'Tan

Doctor Beverly Crusher

Jaron

Lieutenant Worf

Lt Commander Data

Lt Commander Geordi La Forge

Proconsul Neral

Romulan

Sela

Senator Pardek

Spock