Aww, my two armies going head to head... 
Flyers are your friend, use them to null the casket / SSC, or ambush them instead.
Watch out for Scorps. They are bad enough usually, but remember you get no rank bonus when tehy charge you, and will likely hurt your herds.
Fear may be difficult to get around, are you fussed about Marks? Consider Slannesh.
Minotaurs, with 2xHWs should be able to tear through Skellies.
Ill add more as i think...
Flyers are your friend, use them to null the casket / SSC, or ambush them instead.
Watch out for Scorps. They are bad enough usually, but remember you get no rank bonus when tehy charge you, and will likely hurt your herds.
Fear may be difficult to get around, are you fussed about Marks? Consider Slannesh.
Minotaurs, with 2xHWs should be able to tear through Skellies.
Ill add more as i think...