If you're worried about getting this trophy/achievement there are a couple easy ways to do it. These are explained in length on InfiniteStart.com, but the basic gist is finding a boss you know can be completed with relative ease. Speaking for myself, these are the first world bosses Legion, Mother Mind and Shrewd.
The basic tactic is extremely simple. Put Firestorm, a mod that comes from an item you obtain from killing The Red Prince, and make a build that maximizes mod damage. Do NOT invest heavily in mod generation as a second Firestorm is what stopped this from being a Shrewd guide. I showed my "exact" build, as in the build I'd use if I recalled putting all my mod damaging mods on a different relic, but everything else is correct.
Your basic goal is to shoot Firestorm immediately (or after buffs) and then run to a place where the eye can't see you. Staying visible for an extended period of time will do damage and ruin the run. While hiding shoot the adds and get ready to dodge the slam. It's very easy to mess up if you're focused on shooting, so don't be afraid to play it safe.
After this the boss will spawn three enemies (two normal guys and an exploder) while also doing the eye move. You want to basically kill the adds, safely damage the boss, and pay attention to the dodge. It all sounds a lot harder than it actually is. Especially since I am not quite peak power and still did it.
That said there is a Hail Mary play if you're not the best. What you need to do is find one of the aforementioned bosses and then play in another person's world. Worlds generate at players level when they find it, so this could easily be a two world instead of 20 or whatever. If you don't want to beat the game with someone else, investing heavily in weapons can increase your level beyond that of the area. The only thing to keep in mind is this is a single shot basically.
When I did a power level 17 Firestorm to this boss at power level 2 it killed the boss in about three seconds. It was enough to take damage from the gaze, but not long enough for adds or the slam to occur. It also died a moment after, which is why I say it's a one shot thing. You'll kill it in moments, but literally any mistake will likely ruin your one chance. This can be mitigated by opening multiple dungeons at that level, just no guarantee they will be as easy.