Vampire Survivors

All weapons are evolved in the same way. First, you need to get that weapon to its max level (level 8 for almost every weapon). This is done either by leveling up or opening a treasure chest. At the same time, you also need to acquire the corresponding item/weapon needed to evolve or unify that weapon (more detail below). The item does not need to be leveled up at all to evolve a weapon. Only weapons need to be at max level. Items just need to be acquired at all.

Once you get it to its max level and have the corresponding weapon/item, it can now be evolved. However, the only way to evolve it is to have its evolution show up in a treasure chest; you can't evolve it from leveling up. You'll therefore need to last long enough to level up multiple times, hoping the item/weapon you're after shows up enough to upgrade it to level 8. Then, you need to wait for special enemie to show up that drop treasure chests when defeated, such as glowing bats. And then, you need to hope that the chest gives you the evolution of your level 8 weapon.

Once you collect the Grim Grimoire relic (refer to Grim Grimoire (5G)), you'll be able to pause the game and see the progress you've made on discovering each evolution and union. To remove the trial and error/guessing from it, here is a screenshot of my completed Grimoire, so you can see which items you need in order to be able evolve or unify each weapon in the game.


The first column and the first five entries in the second column are very straightforward: get the weapon on the left to level 8, and find the item on the right (doesn't matter what level it is), and then open a chest and hope to get the evolution from it.

The sixth entry in the second column is the first unification, which is of Peachonne and Ebony Wings. Unlike the others, here both weapons need to be at level 8. No item is involved, so get both weapons, get them both to level 8, and then open a chest and hope for the unification.

The seventh entry requires three things. This one is far easier to do by playing as Pugnala, because she starts with both weapons. Then, you need to get both of those weapons to level 8 and also find the Tiragisu item, so this one requires a little more leveling and work.

In the third column, the first three entries are back to the normal formula, but each of those weapons is only available once you unlock the characters that start with those weapons, namely Giovanna, Poppea, and Concetta for the Gatti Amari, Song of Mana, and Shadow Pinion, respectively. You can simply play as each of those characters to start with the weapons you need to evolve, but after surviving 15 minutes with each character, you'll unlock their starting weapon for use by any character.

The next two items in the third column are for the evolutions of the Clock Lancet and the Laurel. These aren't possible (and won't be displayed in your Grim Grimoire) unlock you acquire the Yellow Sign relic. Refer to I can't see anything... (50G) for getting it. Once you get the Yellow Sign, every stage you play will now have four new items on your map that you can track down and pick up: Gold Ring, Silver Ring, Metaglio Left, and Metaglio Right. For these two evolutions, you need to get all three items pictures to max level. So, for the Infinite Corridor (the Clock Lancet's evolution), you need to get the Clock Lancet, Gold Ring, and Silver Ring all to max level, then open a chest and hope for the evolution. Same goes for the Laurel and its evolution. This is most easily done for the first time on the Inlaid Library, since it's just left and right you need to travel, rather than all around a map. I highly recommend doing these there.

The sixth entry in the third column is the union of the Vento Sancro with the Bloody Tear. To unlock the Vento Sancro, you'll need to play as Zi'Assunta. His starting weapon is the Vento Sanco. Once you survive 15 minutes with him, the Vento Sancro will be available to all characters. For this union then, you need to get the Vento Sancro and get it to level 8, but then you also need to get the Whip, get it to level 8, get the Hollow Heart item so you can evolve the Whip, and evolve the Whip to the Bloody Tear. Once you have the Bloody Tear and a level 8 Vento Sancro, now you can open a treasure chest and hope for the union of the two.

Lastly are the Bracelet evolutions. You'll first need to unlock the Bracelet, as no character starts with it. Refer to Bracelet (5G) for doing so. Once you have it, this weapon just evolves once it's at max level; no item or other weapon is needed. So, you'll need to get the Bracelet, get it to max level, open and chest and evolve it to the Bi-Bracelet, then get the Bi-Bracelet to max level, and finally open another chest to evolve it to the Tri-Bracelet, which will complete that entry.

There are other evolutions and unions in the game, particularly those of secret characters, but they are NOT required for this achievement. Only the ones pictures in the screenshot above are required.