[goatlover]

I think prior to season 6, the Klingons and Romulans tried to destroy the Dominion by taking out Odo's homeworld in a sneak attack. Odo's people turned out to be the rulers of a large empire that sought to conquer solids (non-shapeshifters).

[moosingin3space]

Cardassians, not Klingons.

[cholantesh]

Also when Odo was forced to return to the Link to be judged (end of season 4).