Armor Class
18
(natural armor)
Hit Points
246
(36d12 + 12)
Speed
0 ft., swim 120 ft.
STR
24
(+7)
DEX
10
(+0)
CON
18
(+4)
INT
5
(-3)
WIS
14
(+2)
CHA
7
(-2)
Skills
Perception +4
Senses
Blindsight 120 ft., Passive Perception 14
Languages
--
Challenge
6 (2,300 XP)
Proficiency Bonus
+3
Echolocation. The whale can't use its blindsight while deafened.
Hold Breath. The whale can hold its breath for 90 minutes.
Keen Hearing. The whale has advantage on Wisdom (Perception) checks that rely on hearing.
Actions
Bite. Melee Weapon Attack: +6 to hit, reach 10 ft., one target. Hit: 55 (15d6 + 4) bludgeoning damage.
Description
100 ft long, 15 ft high, 15 ft across
This poor whale has some Math issues:
Hit Points: must be 522 (36d20 + 144) a looot of Hp. or if you want preserve the hit points, then must be 246 (17d20 + 68)
Skill: Perception must be +5, because the proficinecy bonus of CR 6 creature is +3, plus +2 Wisdom modifier. Passive Perspetion 15
Attack: The whale is using Strength to attack, then +7 by Strength modifier plus +3 Proficiency bonus by CR 6 creature, must be Melee Weapon Attack: +10 to hit.
CR: this whale with 246 hit points, AC 18, attack +6 and 55 average has a calculated CR 10 (+4 Porficiency)
Baleen whales also don't bite they ram.