Roll 20d600: 375, 557, 430, 182, 393, 447, 465, 218, 374, 260, 26, 285, 142, 224, 349, 6, 406, 479, 412, 280
Tyranitar: -9 HP (Stealth Rock)
Tyranitar summoned a Sandstorm (-10 EN)
Field: Sandstorm (4r)
Action One
Tyranitar used Rock Slide!
Crit [1-25/600]: 375 (No)
Flinch [1-180/600]: 557 (No)
Damage: (8+3+10-8)*1.5+4 = 23.5 ->
24
5 EN
Abomasnow used Sheer Cold!
Hit [1-180/600]: 430 (No)
But it missed!
17 EN
Abomasnow: -2 HP (Sandstorm)
Action Two
Tyranitar used Rock Slide!
Crit [1-25/600]: 182 (No)
Flinch [1-180/600]: 393 (No)
Damage: (8+3+10-8)*1.5+4 = 23.5 ->
24
9 EN
Abomasnow is Knocked Out!