an asp

• -560, -90, -52
• 0, 0, 20318 (seen once) (2 of 29 spawns here)
• -585, 439, -51 (seen once)
• -904, 2972, -9 (seen once)
• -826, 2493, -23 (seen once)
• -771, 1682, -44 (seen once)
• -608, 1322, -51 (seen once)
• -477, 981, -51 (seen once)
• -634, 913, -51 (seen once)
• -747, 942, -51 (seen once)
• -564, 706, -37 (seen once)
• -474, 282, -30 (seen once)
• -622, 1944, -51 (seen once)
• -646, 1276, -51 (seen once) (1 of 2 spawns here)
• -869, -676, -47 (seen once)
• -734, -1185, -51 (seen once)
• -587, 2394, -31 (seen once)
• -870, 2923, -22 (seen once)
• -662, -90, -51 (seen once)
• -593, 823, -39 (seen once)
• -739, 1342, -51 (seen once)
• -899, 3126, -9 (seen once)
• -768, 867, -51 (seen once) (1 of 2 spawns here)
• -659, 991, -51 (seen once)
• -610, 3362, -40 (seen once) (1 of 2 spawns here)
• -947, 3767, -49 (seen once)

As /loc gives them: Y, X, Z, the most used first; nearby spawns share a spot, and one seen in a single visit may be where the mob had been pulled to.