The Cyberdemon may have been a good test of player fundamentals, but that towering monstrosity was just the first boss. It was a relatively simple fight by design — the battle against the Hell Guards, on the other hand, is a bit more complicated.
Much like the Cyberdemon, there are two separate phases in the Hell Guards fight — what's different is the number of combatants. The Cyberdemon was one massive target, and the Hell Guards start off the same way — but for the second half of the fight, players will have to take on two separate Hell Guards at the same time.
That's not to say that the singular Hell Guard isn't a threat: players will need to time their shots perfectly in order to make it past the boss' shield. Overwhelming firepower may have been enough to kill the Cyberdemon, but for the Hell Guards, players will have to worry about more than just their aim and ammo counts.
Given that the rest of the game is about firing away with reckless abandon, the sudden change of pace can be quite the surprise — so, if you've been having trouble taking down the Hell Guards, our video guide should be able to help:
Again, the first phase of the fight is all about counterattacking when the Hell Guard's shield is down. It's hard to miss — if there's no glowing green aura surrounding the boss, then it's a good time to open fire. If you have the ammo available, the BFG 9000 can also get past the Hell Guard's shield — but with such limited ammunition, it's probably best to rely more on timing than anything else.
For the second half of the fight, you won't have to worry about the shield — you will, however, have to worry about twice as many attacks at the same time. It's a lot to keep track of, but if you can manage to keep your distance, avoiding the Hell Guards' attacks shouldn't be too tough. Just aim for their chest and open fire, and they should go down without too much trouble.