Workout

Warm up (600)
400 choice
200 IM drill

Set (600)
4 x 150 on 2:30
...50 swim/kick/swim  

Set (1800)
3 rounds
2 x 75 build on 1:20
2 x 50 pace on :40
2 x 100 on 1:30
...hold steady pace 
150 FAST on 2:00 
...descend 150s by round
Rest 1:00 between rds 

Cool-down (200)