The number of cats you have is the prefix, and saddest warrior death is the suffix.
Number of Cats:
0: Shrew
1: Rose
2: Hazel
3: Lion
4: Heather
5: Breeze
6: Vole
7: Crow
8: Rabbit
9: Swift
10+: Moss
Saddest Death:
Mosskit: leap
Snowkit: shade
Snowfur: tail
Firestar: flame
Swiftpaw: claw
Feathertail: heart
Silverstream: fur
Redtail: foot
Other/none: nose
Comment the name you get!