the age of BOB

Stage 1 {p/c} put a +1/+1 counter on target
creature with the subname BOB
Stage 2 {p/c}{p/c}each defending player destroys a
target creature without the subname BOB
Stage 3 {p/c}{p/c}{p/c}you gain life equal to the number
of creatures with the subname BOB
Stage 4 {p/c}{p/c}{p/c}{p/c}{p/c} target player sacrifices all creatures without the subname BOB
on this permanent when you activate Stage 4 sacrifice the age of BOB