L D U2 B'
R F2 D B2 D'//4a1 2e (9)
(U2 L') U2 L' F2 U2 F2 L
U2//18 to slice and yes I found it this way 

+2 final rip

I did not try the S2 extension that wouldve given 19 oops

other:

U2 L D B
(L D' R D' R' D)//4b2 4e

L (D' L')
(D B U F2 L2 B' D)//2c3 6e