Swim sets getting harder

This one upcoming tomorrow - try it out and tell me how it feels:

400 warm-up
200 drill (your choice)
8 X 100; descending (each rep faster than the prior one), 15" rest
6 X 75; descending, 15" rest
4 X 50 @ L5 (all out sprint), 20" rest
200 cool down

Shout out to Auntie Corina and Uncle Dave, who very precisely alloted $4/km covered, resulting in a $206 donation! Thanks guys!