This can be a little tricky, but i think the best place to do this is at the very end of the Scorched City level (after disabling the sentry) where you meet up again with the purple light character (Starthing) and are trying to get into the castle, but the doorway is suddenly blocked off and you have fight off a few waves of enemies before escaping down the drain.
At the start of this page / checkpoint, when the first wave of enemies spawns, quickly head up the stairs to the right to take out the Scorcher that spawns from the cave. Then, underneath you a Ticker should appear out of the cave below. Immediately lean forwards and try to take control of it using your blue orb (PS4 controller) by holding down L2 / R2. After capturing it, make sure you continue to hold down L2 / R2 for the next few minutes whilst you go about clearing enemies and setting up the 2 Screechers for their untimely demise! It doesn't matter where you position the Ticker, but I just defaulted my hands back on to my lap, which brought the ticker to the front of the screen, which is actually quite a good place for it to hang out whilst you get yourself sorted.
Now, from here you should have 2 Screechers (crab-like enemies) coming up the stairs to attack you, however, you want to keep both of these alive, but you want to get them both down to 1 hit from death. This means you will need to hit each of them 3 times as they require 4 hits to die. If you can do this whilst still up on the top platform, then that's great. However, don't worry if you cannot, as other enemies will be spawning and trying to attack you. But, it can be difficult to remember how many times you have hit the Screechers if you one get 1 or 2 hits in, not to mention remembering which one is which, since they look identical, so if you cannot guarantee that you can get both 3 hits on both of them up here, then i would just totally leave them alone and not even try to hit them until you have dealt with all the other enemies.
Now, as mentioned above, you'll want to take out all the other enemies that are spawning (the Scorchers up top on the left and right, and the Tickers from the left and right caves on the ground level), BUT make sure you keep the 2 Screeches alive AND make sure your controlled Ticker is still safely alive as well (keep holding L2 / R2).
Once you have cleared the waves so that no more enemies are spawning, you should be left with just the 2 Screeches and your controlled Ticker. If you haven't had chance to wear down the 2 Screechers by hitting each of them 3 times already, then now should be the easiest time to do that. Once you are sure that each Screecher is 1 hit from death, you need to try to group them as close a possible, which you can do by getting one to attack you and just evading in a circle around them so that the second one can catch up. Once they are pretty close together, you now need to lead them towards your Ticker.
One thing to remember with the Ticker is that once you relinquish control of it by releasing L2 / R2, it takes a few seconds to actually explode. This delayed explosion can really mess you up when going for this trophy, so just bear this in mind.
I found a good strategy was to place the Ticker just in front of the foot of the stairs on the right, then i would try to group the Screechers somewhere on the left of the screen. Then i would head for the stairs on the right, and i would stand just in front, but slightly alongside the Ticker at the foot of the stairs and wait. The Screechers will likely be approaching you with one in front of the other, and really you need them as close as possible, so you want the let the first Screecher approach you and to try to lunge at you. When it lunges as you, evade backwards, so that you are starting to go up the stairs. At the same time it's about to lunge and you are about to evade, let go of R2/L2. If done correctly, the Screecher that lunged at you should be alongside the Ticker, and the Screecher behind, should be right behind. The second or two delay for the Ticker to expose should mean that it does so when the Screechers are both within the blast radius and die along with the Ticker.
As long as the blast kills both of the Screechers and obviously the Ticker itself, this trophy will be yours. The delayed blast can sometimes mean that 1 of the Screechers just manages to get outside the blast zone and ruin your attempt for this trophy, but if you keep trying you will get this fairly easily once you are familiar with the delayed explosion.
Wow, so this explanation turned in to War & Peace. Apologies for the waffling, but hope this helps someone out.