Could it be another Wolf 359?

After a couple more hours of planning, the heroes and their supporting troops attacked. They did take several precautions, chief of which was to make themselves invisible. They also summoned 8 flying eagles and loaded one of their ships with explosive oil in the hopes of ramming it into Vecna's ship.

The first couple rounds of combat ended up being pretty loose with opposing die rolls deciding a lot. One of the vessels was immediately crushed by Falazure, the dracolich exarch of Vecna. The allies slipped 8 of their invisible gold dragons under the defenses of the massive ship and they were able to destroy or damage most of the catapults on that side of the ship.

After a couple rounds, the heroes made their move, using an arcane gate created by Marovic, they transported right to the stairs heading below deck, and hopefully to Osterneth.

As an aside, had the heroes not been invisible, Falazure would have targeted them immediately, and that would have been ugly.