This can get kind of complicted: Ties of Blood and Water
is an important Dominion episode in that it re-introduces Weyoun, but to appreciate it you really need to have already seen Second Skin
, which doesn't feature the Dominion at all. Then there's Blaze of Glory
, which is set against the backdrop of impending war with the Dominion and uses the Jem'Hadar as baddies, but is also the end of a three episode story arc, the first parts of which have no Dominion involvement.