Workout

Warm-up (500)
500 choice

Set (400)
2 x 200 
...30 rest between
…200 breast alt 50 swim/50 kick
…200 back alt 50 swim/50 kick

Set (600)
3 rounds
4 x 50 on 1:00
…fly/back; back/breast; 
…breast/free; free/fly

Set
4 rounds (1200)
100 IM on 1:30
4 x 50
…odd rounds 50s on :40
…even rounds 50s on :50
…even rounds are stroke/free

Cool-down
200 EZ choice