Here is some informations Arcon. 
Greek Assassin is unit which you send as Political attack

Political Attack via Greek Assassin

 Who: Greek Assassin

What: A single-use stealth (invisible to the receiver) "bomb" doing 12,600 damage each and taking no resources from the target Archon's City. You may send up to 10 at a time to maximize the damage done. You may send up to 10 Launches a day.

The Sender cannot recall a Political Attack once it has been launched.

The target City can only defend against a Political Attack by having initiated a Protection “dome” which is available for purchase, using either Drachmas or Glory Points.

The attack leaves behind a Green cloud and flies appear to circle your City, for a while, until the cloud eventually dissipates.

Where: You must be Level 40 in order to purchase Greek Assassins from the Black Market. Look under the Units -> Offense tab, they are the first unit and cost 500 Drachmas, unless you catch a sale or receive some in a purchase package deal. After purchase, they will be stored in Inventory in your War Council, under the Tab for Political Unit.

When: Arrives at the other Archon's City within 3 minutes, no matter how far away the target Archon’s City is from your City. Time to target may be less than 3 minutes, depending on the distance to target.

Why: Used when you don't want to make a long march but want the other Archon to know they are on your radar, used to soften up the other Archon's Defense before your Offense lands, used whenever and wherever you choose to pay the cost of each Greek Assassin.

How: To send a PA (Political Attack) Go to the Map and select the City you want to attack, click on the Green Potion - http://prntscr.com/7a7uw2 and then select the number you want to send (up to 10) and then send. Alternatively, you can choose to enter the other Archon’s City and select Order Political Attack. http://prntscr.com/asm3r7, then select the number you want to send (up to 10) and then send.

So..only Political Attack is with Greek Assassin.