This one is kind of obvious but King+Tycoon is great.

Assassin+Navigator+Saboteur = Hitman
An addition to the Queen hunter, except that when the enemy has a pirate, the saboteur will just redirect the offending sub, allowing you to continue on your path to hunt down their Queen!

Navigator+Smuggler+VIP = Escape Artist
Delivering a valuable specialist near enemies? As soon as a pirate targets you, just redirect to a friendly outpost and zoom away; the pirate will never catch you and you can then set up a defense to defeat the pirate's sub.

Unfortunately, in the last update they killed the diplomat/sabatour. Now the diplomat only frees specialists while held at enemy outposts (found out the hard way while being attacked and having Diplo/princess/4 sabs).
Note that now when a sab is used, it is placed 1 tick ahead of the returning force, so Big Ds defense also no longer works

All these combo's.... No longer panda's secret.