Victor Vran

This was one the last achievements that I got (posting the same guide here as Thunder and Lightning), based on it being completely reliant on random drops. After finishing all other achievements and logging 200 hours in the game, I'd gotten two legendary revolvers and two silver bullets, but no Gunslingers. These cards supposedly only drop when in the Motorhead world, and the best place to farm cards there is either via a high concentration of champions (such as Windswept Canyon) or the Queen of the Damned, as she is guaranteed to drop at least 4 cards.

I focused on the Queen of the Damned farm for hours at a time over several days but never got the card I needed. I got pretty efficient at it though, using a strategy I learned from Bloonis that used a maxed out Ember charm paired while having a Berserk Aura-buffed maxed out hammer equipped and an offhand weapon that had maxed out luck and extraordinary luck. You can [almost] one-shot her [most of the time]. While you get lots of cards quickly, I didn't get any of the ones that I wanted (Bloonis didn't either).

In the end, I got the card I wanted from a legendary chest that I opened while inside the Motorhead world (don't open them anywhere else!). I stockpiled chests by leveling hard-mode (not hardcore) characters in the Den of the Broodmother, where I would run around and kill 95% of the spiders/eggs and then let the boss kill me, thus resetting the eggs and starting all over. I could usually get the character to around level 16 (using stashed loot, of course) before I was 5 stars for all five hexes which yields almost 3 legendary chests in the end after transmuting everything (mostly from the 3-5 star levels of the hexes). If you have a second character logged in at the same time, you double your yield. The second character dies almost as soon as he is revived every time, but still gets XP and credit for the hex kills. Any build should work, but the one that I found to be most efficient used a legendary shockwave demon power with the cavalier armor (maxed to 180 recharge rate) with the maximum number of tower cards per level and a Needle (125% recharge rate, but you can use any low level zealous weapon maxed to 110% recharge rate).

I found both of these farming methods boring and tedious, making me start to hate playing this game, so I saved up ~20 legendary chests, backed up my save game to the cloud, opened up all 20 chests at once and then reloaded from the cloud if I didn't get a card I wanted (On Xbox, open up manage games and delete your local copy of the save before quitting the game; quitting the game saves to cloud and overwrites your cloud save). I gave in and used the same approach to the Thunder and Lightning achievement. Had to open ~200 legendary chests to get what I needed, making these the most poorly designed achievements in the game and explaining why almost no one has them.

The gunslinger and silver bullet are both classified as weapon enhancing destiny cards. Equip them and a legendary revolver for this achievement.