The Similarities
Swarm Tactics and Decoy both effect ships at Range 1 of the pilot using the EPT (hereafter referred to as "the Caster").
Swarm Tactics and Decoy both take the EPT slot
Swarm Tactics and Decoy both cost 2 points.
Swarm Tactics and Decoy both bring the target up to the Caster's current level in the attack phase.
The Differences
Decoy can also effect ships at Range 2
Decoy lowers the Caster's down to where the target's was in the attack phase.
Decoy seems to free the pilots from flying in as tight of a formation, at the expense of the drop in pilot-skill from the Caster.
Given that Decoy is a zero-sum bonus, it is a more situational upgrade, even if those situations are plentiful and it is less stringent in its range requirement.
The Combo
Green Squadron Pilots can take both.
Decoy and Swarm Tactics trigger at the same event (the start of the combat phase) ; the order of the operations is up to the fleet commander in its resolution.
When Swarm Tactics would be the most useful option, you can Decoy the higher-PS ship, and then Swarm Tactics it back up to its original Pilot skill.
This has the same effect as if the High-PS pilot had Swarm Tactics, except that it can be used off of any high-PS pilot, and the high-PS pilot still has an open EPT slot. Therefore, your GSP enjoys a boosted Pilot Skill opportunity unless you've simply flown out of R1 of all pilots with PS>4.
When Decoy would be valuable (e.g. the high-PS pilot does not have a shot), you may then use Swarm Tactics to boost a second allied ship with the high-PS you've leeched.
Also, this also opens up the tactical decision of "Do I have another ship that would love to have Decoy right now to make sure it attacks this round, even at Range 3?"
There are probably better combos than this for a double-EPT. For that matter, there are probably better ways to spend 4 points on an EPT in general. However, this is a very interesting disambiguation and interaction that I thought I'd share with you guys ![]()