Ultra Combos are things I've tried and have worked well for me, I only intend to publish here as I use some of the synergies of my crews, this isn't a tactica hammering exercise, everything here has been tried and tested.
So onto combo 1
The Seamus Swicherroo
Seamus and the copycat killer share one fantastic ranged weapon, the .50 flintlock. I've heard this branded as one of the best ranged weapons in the game and its damage output is certainly high at 4/6/7, there are other characters that can put out more damage, but that will all cost you more action points. In a single action, I'm struggling to think of a better ranged weapon, and with two of your crew wielding one, you have the opportunity to fell some fairly big opponents.
The downside however is the flintlock is a single shot weapon and its for that reason that this combo can be very useful.
What is the Switcherroo?
The Seamus switcherroo comes from the ability on the copycat's card to allow him to trade places with Seamus for a 1 action. Mistaken Identity is the CCK's only personal spell but is cast on a 9 of tomes, with no resist, it allows Seamus and the CCK to immediately switch places if they are within 15" of each other, which is almost half the board.
When to use
Using the Switcherroo is very situational, but for me there have been four circumstances where its worked well.
"I'll save you master!"
If you have something nasty bearing down on an injured Seamus then a shot from each, and a switch can keep Seamus safe. You'll likely be throwing the CCK under a bus, but hey at least he generates you a corpse counter, so he can come back as a belle or a dead doxy.
"Be a good boy and go be the bait"
A somewhat riskier proposition is to use the CCK as bait, team him up with some chaff to deter any charges and keep him out of enemy fire, then as your prey is bearing down, pull out the Dirty Harry and loose a shot, before switching places and sending Seamus in for the kill.
"Master, it's over here!"
Getting round the board can be a lot easier if you use switch to place Seamus exactly where he needs to be. You could run the CCK up to an objective, or into your opponents deployment zone, and they think you the fool for sending an insignificant totem to do their masters work, but then that 15" switch kicks in and Seamus is exactly where he needs to be with 3 AP to get the job done. This could be particularly useful for something like treasure hunt where it takes two actions to pick up!
"My little friend"
The Resser scheme My Little Friend requires the Switcherroo to be successful IMHO. You need to keep the CCK safe and then use him for the kill. What could be better than switching him into the right place when Seamus has softened up his victim?
9 tomes for mistaken identity
2 Higher cards for hit and damage for the CCK when firing the flintlock
A high card and a soulstone or a focus action to get Seamus's shot over the line
Remember both Seamus and the CCK have access to the one action spell 'live for the pain'. Whilst it doesn't have the damage output, inflicting damage will rejuvenate an equivalent number of wounds. Useful for a finishing combo and it'll help the CCK to recover the wounds he picks up from firing that big old hand cannon.