I've surprised myself by coming up with some pretty tough workouts recently. The most recent one was the following.
3 Sets: 2 Failure
Push-ups
Bicycle
3-way lunge
Wild card push-up (anything besides a regular push-up)
2 down, 1 up
Wall squat
Rope
Tire/Wall Knee 2 Elbow
Dips

I only actually made it through two sets. I was doing it so I wasn't killing myself, but once I couldn't do more of something without taking a break, I'd move on. For the wild card push-up I did Archer Push-ups first, then staggered push-ups. I don't know how to describe the 2 down, 1 up exercise other than to post a video. It is an ab exercise. Basically while laying on your back, a single leg raise (other leg held straight out, but off the floor) with with a hip raise at the end. The Tire/Wall Knee 2 Elbow is a standard plank position hold where you bring your knee to the opposite elbow, but you either place your feet on the wall so your body is perfectly horizontal, or on the tire or a chair or something. The corresponding exercise to that last one is an elbow plank, then touch one hand to opposite hip, without rotating your hips. This transition from 4-point to 3-point plank and back without rotating is surprisingly difficult.

I like the hip raise idea. I'm all ears for ab exercises that I'll be able to feel right away. Those 2 down, 1 ups are brutal. As a side note, I take a lot of stuff from Athlean-X Xero workouts.