This position is slightly modified from a club game between M. Feldman and M. Noonan. White had a commanding lead, but tried to attack black too quickly and became entangled in a messy fight.
How can black get the big kill?
(;AW[cb][eb][dc][gc][pe][re][ef][qf][eg][rg][eh][gh][ph][qh][ei][fi][gi][cj][gj][ij][kj][gk][hk][jk][fl][gl][ql][bm][cm][fm][jm][mm][fn][in][nn][eo][fo][ho][io][ko][lo][mo][po][qo][hp][jp][eq][fq][mq][oq][pq][dr][fr][lr][cs][es][fs]AB[cc][nc][cd][fd][gd][pd][qd][rd][de][qe][df][of][fg][gg][hg][ch][fh][hh][rh][di][hi][qi][dj][ej][fj][hj][ik][el][hl][il][em][gm][im][bn][cn][dn][gn][go][no][dp][gp][ip][lp][mp][np][qp][dq][gq][hq][iq][kq][br][cr][gr][kr][gs]SZ[19]
(;B[ir];W[ks])
(;B[nr];W[nq];B[ls];W[jq];B[jr];W[is];B[mr];W[lq];B[or];W[pr]C[Not a chance!])
(;B[is];W[ks]C[White's secret weapon.]
(;B[js];W[hr])
(;B[hr];W[jr];B[jq];W[js];B[nq];W[nr];B[lq];W[ms]
(;B[or];W[ls];B[pr];W[qr]C[Difficult ko. Black can do better.])
(;B[mr];W[ls]
(;B[ir];W[mq];B[or];W[pr]C[Difficult ko. Black can do better.])
(;B[or];W[mq];B[ir];W[pr]C[Difficult ko. Black can do better.]))))
(;B[ks];W[jq]
(;B[ir];W[jr])
(;B[is];W[jr])
(;B[jr];W[is]
(;B[ir];W[hs];B[mr];W[nr];B[ms]
(;W[nq]C[CHOICE];B[lq]C[RIGHT])
(;W[ns]C[CHOICE];B[ls]C[RIGHT]))
(;B[mr];W[nr];B[ms];W[nq];B[lq];W[ir]
(;B[js];W[hm];B[hn];W[jl];B[hm];W[fp]C[Temporary seki, but black is doomed.])
(;B[hr];W[hm]C[Black can't afford to let white capture!];B[hn];W[jl];B[hm];W[fp];B[js];W[hs])
(;B[hs];W[hm]C[Black can't afford to let white capture!];B[hn];W[jl];B[hm];W[fp];B[js];W[hr]))))
(;B[jq];W[ks];B[is];W[hr];B[js];W[ir])
(;B[mr];W[nr]
(;B[is];W[ks]
(;B[hr];W[jr];B[js];W[jq];B[ls];W[ms])
(;B[js];W[hr];B[ms];W[ns];B[ls];W[ks]))
(;B[ks];W[jq];B[jr];W[is];B[ir];W[hs];B[ms];W[nq];B[lq]C[RIGHT])
(;B[ms];W[ns]
(;B[ks];W[jq];B[jr];W[is]
(;B[ir];W[hs];B[ls]C[RIGHT])
(;B[ls];W[nq]
(;B[lq];W[ir];B[js];W[hm]C[Black can't afford to lose these stones!];B[hn];W[jl];B[hm];W[fp]C[Seki inside, but black dies on the outside.])
(;B[ir];W[hs];B[lq]C[RIGHT])))
(;B[jq];W[ks];B[js];W[ir];B[ls];W[ks]))))