Realizing that key parts of this picture are symmetric made it not so difficult - the 50th possibility was it! O:)
SPOILER: r21/c11-12,13-16,21-22,24-25 r22/c5-6,c8-10,c13,c17,c20,c23 r23/c3-4,c7,c18-19 r24/c2 r25/c1 The gate in top right corner is symmetric, as well as the angel (r19/c11-12,c16-17, r13/c6,c8-9,c12,c14,c16,c19-20,c22), and to the left is a cloud (r4/c3-5, r5/c1-2,c6, r6/c5). Hope it helps.
SPOILER:
r21/c11-12,13-16,21-22,24-25
r22/c5-6,c8-10,c13,c17,c20,c23
r23/c3-4,c7,c18-19
r24/c2
r25/c1
The gate in top right corner is symmetric, as well as the angel (r19/c11-12,c16-17, r13/c6,c8-9,c12,c14,c16,c19-20,c22), and to the left is a cloud (r4/c3-5, r5/c1-2,c6, r6/c5).
Hope it helps.