1) Brutality 2) Callousness 3) Group of ravens 4) Harshness 5) Heartlessness 6) Insensitiveness 7) Insensitivity 8) Lack of sympathy 9) Malice 10) Meanness 11) Mercilessness 12) Nastiness 13) Ruthlessness 14) Spite 15) Spitefulness 16) Viciousness 17) Vindictiveness 1) Cruelty 2) Inconsiderateness 3) Inconsideration 4) Malevolence 5) Malice 6) Spite 7) Thoughtlessness 8) Unhelpfulness 9) Unkindliness 
Unkindness is the collective noun for a group of ravens.
[n] - lack of sympathy
describes a flock or group of ravens.
noun lack of sympathy