Terrence Howard is ratcheting up his legal war with his former talent agents ... claiming they failed to let him know about a chance at getting his own signature fragrance and potentially becoming a Home Shopping Network star.

The actor makes the new claim in a declaration he filed as part of his legal battle with his former talent agency, CAA. Terrence previously sued CAA, claiming they messed up his salary negotiations for "Empire."

Terrence, who played Lucious Lyon on "Empire" for six seasons, claimed the agency did not adequately represent his best interests when negotiating his deal with FOX.

In his declaration, Terrence said his agents asked FOX for an increase in salary ... asking for $750K per episode. He claimed FOX declined the request and said they could not go above $325K per episode.

However, Terrence claims his agents never told him "Empire" fragrance representatives had mentioned a potential Terrence-branded "Empire" fragrance deal ... which he says included a $20K payday for a launch event, potential future paid appearances, an HSN appearance, and a possible men's signature-fragrance venture.

Terrence said he was forced to make a decision on his contract without having all the relevant information ... and he blames CAA.

For their part, CAA has denied they're responsible and they're trying to get the case thrown out, arguing, in part, that Howard's claims were brought past the statute of limitations.