It is perfectly possible (and not particularly difficult) to get this achievement on your first playthrough of this DLC. In both DLCs, you can play Extra Life mode from the start. You should play on I'm Too Young Too Die, which is the lowest difficulty. You don’t need to be great at the game to finish with more than 5 extra lives. I personally finished Ancient Gods 2 with 13 extra lives. First of all, you’ll want to collect all the extra lives available in each level of the DLC. I used the text guides located here:
https://gameranx.com/features/id/219285/article/doom-eternal...https://gameranx.com/features/id/219335/article/doom-eternal...https://gameranx.com/features/id/219336/article/doom-eternal...I would like to offer some combat-specific tips. A lot of the enemies you fight will be the same enemies you fought in the main campaign. I mainly used the Super Shotgun, Ballista and Rocket Launcher with lock-on mod as my primary weapons for dispatching Super Heavy enemies. These should be your priority whenever they appear. Use Ice Bomb to regain health, Chainsaw weak demons to refill your ammo, and use Flame Belch or the Super Shotgun's Meat Hook to regain armor. You can combine these with the Sentinel Hammer to get even more health, armor or ammo from enemies. Save Blood Punch for Pinkies, Spectres, Cyber-Mancubi and Doom Hunters. It can also be used to instantly destroy an Archvile's fire wall. Using it on fodder enemies is a waste in my opinion. For runes, I used Seek and Destroy, Blood Fueled, and Dazed and Confused. These increase enemy stagger time (which is the window during which they can be Glory Killed), allow Glory Kills to be performed from further away, and increase movement speed after performing a Glory Kill. All of these are useful in every combat encounter to some extent. The DLC introduces a few new enemies. Each time these enemies appear for the first time, the game gives you a quick tutorial about how to kill them. The new enemies in the DLC are Armored Barons, Stone Imps, Screecher Zombies, Riot Troopers, Cursed Prowlers and Demonic Troopers. Most of these enemies aren't much to worry about, except the Cursed Prowler. Whenever you fight a Cursed Prowler make it your number one priority to kill. If you get hit by one you become cursed, which drains your health and prevents you from jumping or dashing. The only way to kill the Prowler and lift the curse is to use a Blood Punch on it. When fighting Screecher Zombies, be careful not to kill them while there are stronger enemies around them, as when killed they buff all other nearby enemies. The last level has a Screecher Zombie and 2 Marauders together. You don't really want to be fighting 2 buffed Marauders at once, even on the lowest difficulty.
When fighting the final boss, the most important thing is to only attack him when you have Sentinel Hammer ready to use. The only time you can attack without him blocking or countering is when his eyes flash green (similar to Marauders). Hit him with the Ballista or Super Shotgun, then use the Sentinel Hammer to extend the time he is stunned, then quickly switch between the Ballista and Super Shotgun to do as much damage as possible. The boss can regain health if he hits you with his sword, but it's pretty easy to dash away from it. When he summons the fire wolves and hell knight, you can kill the wolves in one hit with the Super Shotgun. The wolves drop Sentinel Hammer energy. In the last 2 phases, he will summon multiple Heavy and Super Heavy enemies at once. You can use the Sentinel Hammer to kill all of them in one shot. If you need health, armor or ammo there are regular zombies that spawn infinitely around the edges of the arena. I managed to beat him without dying once. I personally found some of the regular combat encounters in the DLC to be harder than the final boss.