The one-arm dumbbell floor press is one of my favorite pushing exercises. While it's ostensibly an upper body exercise for the chest, shoulders, and triceps, try it and you'll quickly realize that it's a full-body exercise that requires total body tension to maintain a stable base of support.
It's also a great shoulder-friendly alternative for people who might experience pain with full range of motion pressing, or those with lower extremity injuries that preclude them from pushing through their feet.
The problem, however, is that as you get stronger, it can be tricky to hoist heavy dumbbells into position (and back down onto the floor again) when you're training by yourself. Furthermore, unless you're blessed to train in a gym with extremely heavy dumbbells, it won't be long before you've maxed them out.
Sure you can add reps to a point, but continually using the same weight will inevitably result in a plateau that feels like your own personal version of Groundhog Day. That gets old, fast.
Enter the Landmine Floor Press
The landmine allows for greater loading potential, and because the barbell is already elevated off the ground, it's much easier and safer to get in and out of position. With a simple self-spot from the non-working arm, you should be all set.
The angled barbell still lets you press with the same range of motion as a regular floor press (i.e., until your triceps touches the floor) and it also allows for a neutral grip, which is easier on the shoulders. Moreover, some folks will find that the thicker handle helps to relieve stress on the elbows, which is an added bonus.
You'll have to play around a little bit at first to figure out how close to set up in relation to the bar, so start very light and experiment with different body positions until it feels comfortable. Once you get that squared away though, it shouldn't be long before you're crushing some serious weight.
If you don't have a specific device to secure the barbell, place it carefully in a corner with a heavy dumbbell over the tip to keep it in place.