Tiwi Ld is probably the best in term of his clan, given he's the only DR-comparable card in Frozn. I would have said Bonnie Ld, but Elo banned, DT penalized, low stars. She's really useful only in DM nowadays.
Personal favourite, probably Valentina Ld. Although I am little bit fond of Hopper Ld aswell.
Improvement, Either Lianah Ld to something you described or Naja Ld to Power = Power opp +2.
Hmm i get you, i think Futoshi Ld is brillant, but Tiwi Ld is great just for the pure fact that defeat goes so well.
but Naja Ld is probaly one of the worst.actually i really dont like Krazan Ld. hes probaly the worst in my opinon after Naja Ld. had he been a 5* ld (slim chance, but still) I WOULD HAVE WANTED HIM TO BE a 7/6 with maybe some revenge based ablity. like damage + 2
Futoshi Ld is good, but not the best because he isn't vital for a FPC deck. Shifou has nearly the same ability and Fei/Heitachi fit to the 4* spot.
Same with Harrow Ld, Lois Ld, Valentina Ld, Andy Ld, Dudley Ld, Gail Ld. They're good and playable, but all have alternatives that are at least just as good if not better.
The promblem with most of the ld's is that after Bonnie Ld,people where excpeting so much from them. Had Dudley Ld been a 7/5 or 8/4 with - 2 opp life min /? hen would have been a staple in a clan where there a not solid 4*. Any reason why with the first wave of ld's there wasnt a 5* ld/ as i said Krazan Ld should have been the 7/6 with revenge dmg +2
Futoshi Ld imo is the top choice for the FPC 4*, though him, Fei and Heitachi are pretty close... But COB is usually better than SOB on a higher star card, because you can get more from that win, +2 damage, +2 life, or the Freaks poison even... But Futoshi Ld and Shifou are great when used together
Yes, he's the best 4* but by no means absolutely necessary. Like in this week, someone might favour Heitachi in elo because of Oshitsune being free and still get similar results. Tiwi Ld is probably in 80% of all Frozn builds, not taking Ext. Survivor or really defensive half deck builds into account. Not a major deal, but enough to separate the best from the good.
And yeah, Cob is essentially offensive Sob. Except against Pussycats.