A Farewell to Arms Update

A Farewell to Arms is a free update that was released April 5th, 2019. It features 22 new guns, 14 new items, new synergies, a new secret floor with a new boss, two new Gungeoneers, and various quality of life and balance changes. It does not contain any known achievements, and does not add any new enemy or boss entries in the Ammonomicon.

Enemies

 * All new enemies in this update are not viewable in the Ammonomicon, this includes the new boss.
 * For more info on specific enemies, see the Enemies tab in R&G Dept.

Items

 * Battery Bullets now mentions the accuracy increase in its Ammonomicon entry.
 * Boomerang cooldown significantly lowered.
 * Bottle can store pickups other than ammo and health.
 * Box grants double damage to shots fired while it is active.
 * Devolver Rounds only devolve enemies into Arrow Kin.
 * Full Metal Jacket grants one armor upon pickup.
 * Gunknight Helmet grants two armor upon pickup instead of one.
 * Meatbun now mentions the damage boost in its Ammonomicon entry.
 * Portable Turret has much more health.
 * Robot's Right Hand now mentions the junk damage boost in its Ammonomicon entry.
 * Ruby Bracelet can be taken to the Blacksmith to be permanently upgraded.
 * Scattershot makes each bullet deal 55% of its original damage instead of 40%.
 * Teleporter Prototype instantly kills a random enemy upon teleporting to a room with enemies in it.

Guns

 * Betrayer's Shield damage increased from 6 to 7.
 * Big Shotgun max ammo increased from 50 to 70.
 * Charge Shot magazine size increased from 1 to 5, and max ammo increased from 50 to 75.
 * Crescent Crossbow max ammo increased from 100 to 150.
 * Dark Marker max ammo increased from 200 to 250, and damage increased from 8 to 13.5.
 * Deck4rd max ammo increased from 40 to 60.
 * Devolver only devolves enemies into Arrow Kin.
 * Dragunfire damage increased from 5 to 6.5, and shots pierce. Spread and reload also reduced.
 * Grasschopper now causes mini-Blanks when its shots explode.
 * Grenade Launcher max ammo increased from 25 to 60.
 * Laser Lotus max ammo increased from 100 to 150.
 * Old Goldie max ammo increased from 70 to 150.
 * Orange Guon Stone damage increased from 3 to 5.
 * Plunger fully restores ammo upon reloading when standing on poison.
 * RUBE-ADYNE MK.II damage increased from 8 to 10.
 * Rubenstein's Monster damage increased from 7 to 8.
 * Silencer damage decreased from 13 to 10.
 * Starpew magazine size increased from 1 to 100, also charges much faster.
 * The Emperor damage decreased from 7 to 5.6.
 * Thunderclap damages all enemies around the player when reloading.
 * Trident magazine size increased from 6 to 10.
 * VertebraeK-47 max ammo increased from 250 to 300.
 * Vulcan Cannon damage increased from 4 to 5, magazine size increased from 600 to 900, and max ammo increased from 800 to 900.
 * Zorgun magazine size decreased from 30 to 20, and max ammo increased from 300 to 350.

Quality

 * Book of Chest Anatomy downgraded from to.
 * Clear Guon Stone downgraded from to.
 * Escape Rope downgraded from to.
 * Green Guon Stone downgraded from to.
 * Napalm Strike downgraded from to.
 * Shock Rounds downgraded from to.

Other Features

 * A new NPC named Bowler, who activates Rainbow Mode.
 * Wall and Pedestal Mimics now drop an extra item when killed.
 * The boss DPS cap is raised, meaning that bosses can be killed more quickly.
 * Rebalanced items, with many low-tier items receiving buffs or completely new effects, and items being more consistently powerful.
 * 2 new trophy slots have been added to the room of The Breach containing the Sorceress, Daisuke, and Tonic. One of these is for Bowler, the skull trophy is unlocked by unlocking the Gunslinger.
 * NPCs and shrines that appear in the Gungeon have their own theme songs.
 * New Beholster shrine.
 * Unlock alternate skins for starter guns by beating the character's past with their alternate skin equipped.
 * Boss HP bars fade out when overlapping the player.
 * Crit flash with Vorpal Gun/Vorpal Bullets is less bright.
 * Drill sound from Bullet Bore now much quieter.
 * Better rewards from beating Old King, including a Synergy Chest.
 * The Robot can now spend armor at shrines that cost health.
 * Red chests that give health items now also give you a key.
 * Increased chances of spawning rare rooms (witch cauldron, black market, cleanse shrine).
 * You can pet the Dog.

Links

 * Launch trailer
 * v2.1.0 - v2.1.3 patch notes
 * v2.1.3 - v2.1.6 patch notes
 * v2.1.7+ patch notes