Second attempt at making this work, perhaps a bit more artificial this time.
White has played the marked stone in an attempt to get a ko - show him the error of his ways.
Thanks to Last Evolution for catching a mistake.
(;AB[cs]AB[cr]AB[cq]AB[cp]AB[bp]AW[ar]AW[bo]AW[co]AW[do]AW[dp]AW[dq]AW[dr]C[Black to live unconditionally.]AB[fr]AB[ep]AB[fp]AB[en]AB[dn]AB[cn]AB[bn]AB[br]AW[ap]TR[ap]AB[bl]AB[gr]AW[es]AP[goproblems]
(;B[eq];W[ds];B[aq];W[bq]C[Ko.])
(;B[aq];W[bq]
(;B[as]C[Double ko - white can't win.RIGHT])
(;B[aq]C[NOTTHIS]))
(;B[an];W[aq];B[ao];W[bs]C[An unfavorable ko for white, but black can do better than even this.])
(;B[eo];W[ds];B[aq];W[bq]C[Ko.])
(;B[as];W[aq])
(;B[er];W[ds]
(;B[aq]C[Ko])
(;B[as]C[Ko])))