http://battlecollege.wikispaces.com/mkiiRetribution is a good starting point. Don't take it as gospel, but there's a good general overview of who does what, and how well. Here's the things that I think are good about Ret, from playing against them:
Myrmidons:
Retribution tend to run light on jacks; most of their warcasters want to use their focus for spellcasting. They also have a high cost combined with average durability, so you need to be careful how you apply them. That said, there are some good choices:
--The Phoenix is a good all-rounder. It has an arc node, it can clear infantry with Combustion, and it's got a nice powerful sword for nut-cracking.
--The Banshee & Daemon both have decent melee capabilities, and good guns--the Banshee can knock down your chosen target before your other guys swarm it, and the Daemon is another good infantry clearer. The Banshee's ability to mess with enemy orders is situational, but useful for disrupting Shield Wall units and the like.
--The character heavy Discordia is another good all-rounder, and it's spray attack addresses a traditional Retribution weakness, in Stealth.
Units:
--One of the most feared synergies with Ravyn is the Mage Hunter Strike force, with the Commander unit attachment. She can give them Snipe, and then use her feat to give them boosted attack rolls. On a unit that can shoot through nearly anything, and ignore defensive buffs, they can easily take down warcasters with poor defensive stats who came too far up the board.
--In melee, Dawnguard Sentinels with the unit attachment are quite terrifying. They're not easy to kill, and if they take casualties, the survivors get a free move and attack next turn. On a unit with good
MAT and Weapon Master, you can really punish an opponent that leaves them half-eaten.
--Aiyana & Holt (a two-man mercenary unit who work for Retribution) are a good backup choice, with two very accurate guns added to a spellcaster who can put Magic Weapon where it's needed (if you're facing incorporeal models, Protectorate warjacks guarded by the Choir, etc), or make your chosen target more vulnerable to damage.
Solos:
At least one Arcanist is nearly a must-have. Their Power Booster is useful for getting jacks up the field early on, and Concentrated Power pushes them into the range of power where they can reliably kill or cripple an enemy heavy in one round.
Mage Hunter Assassins are unpredictable little critters. Half the time, they'll do nothing and get killed, the other half they'll take out many times their points and leave your opponent speechless. With their superior melee range, they make a great threat--either have them lurking behind your front line to discourage enemy heavies from getting too close, or looping round the side to make the enemy warcaster or warlock nervous.
Eiryss, Angel of Retribution (the second version of her, the one sitting on the gargoyle) is a very useful solo who can mess with enemy upkeep spells, disrupt warjacks, or take the focus points off a warcaster to drop their armour.
