I don't have a strong skill lineup, and it's leaving me pretty vulnerable to science defenders. I've got Nick and Kate as top rank 6*s, but I don't know what to do with my 7* skill champs.
 Chee'ilth
Chee'ilth: I'd love to rank her up as she's usually a top choice when a bleed champ is needed for content, but I don't know that an R2 Chee'ilth gets me more than Nick on attack, and I'm not optimistic about using her on defense.
Attuma: Not sure if an unascended R2 Attuma would help on defense, though the contact damage helps.  Is he good as an attacker? I 
might be able to scrounge up enough to get him to R3 in time to make a difference this season.
Falcon: 
Lock on might come in handy in some match-ups.  
Shang-chi:  Seems like an all-around choice for attack.  Can he counter Photon?
I could always hold out and hope that I'll open a crystal and get Bullseye or Crossbones, but the odds don't favor it.