NPCs composing that spawngroup :

a_thought_leech (45%)

a_young_thought_leech (45%)

Chasm_Overseer (10%)

NPCs spawning around that spawngroup :
(Max range : 100)

thedeep_a_shrieker34, range=97 (-87,1,-59)

a_deepspore_mushroom (2%)
a_shrieker (98%)

thedeep_a_thought_leech_spiriter166, range=17 (-105,87,-57)

a_thought_leech_spiriter (100%)

thedeep_224972, range=23 (-113,109,-58)

thedeep_224984, range=78 (-143,158,-58)

a_thought_leech_evoker (50%)
a_thought_leech_spiriter (50%)

thedeep_224987, range=20 (-84,117,-61)

a_thought_leech_spiriter (50%)
a_young_thought_leech (50%)