Arterial of Origins:Alchemy

You perform alchemy to generate new cards from material cards and lower level cards. Alchemy first becomes available in the 4th chapter at the same time as the world map. New choices are unlocked when ally characters' skills level up or sometimes by creating a weaker version of an equip item.

Material Harvesting Tips
All the colored stones and fragments can be bought in the suspicious store (with the guns) after fully completing the 2nd arena. This requirement also unlocks all colors of cloth at the school store. This 2nd arena has the cute wolf-girl host nicknamed A-chan and only appears after fully completing the first arena.

Harvesting monsters as materials for higher level rings can be time-consuming so learn to make good use of auto-battle, and Lily (who also captures). Battle may also be sped up by pressing the battle mode button which makes the game skip animations. This is the top-most button on the bottom-left of the battle screen.

Emilio's position shuffling ability can help you capture cards in the back which refuse to move. Mirai's ability is also useful as it captures x dead cards that Syuya didn't kill.

Note that mobs tend to be sparse in the final chapter so don't wait to harvest anything. Gold puttetes seem to be mostly in the normal route in the map where Sayane was heading to Gillezel's castle. Ryuka Frosts and Lv3 mud-girls can be found in the map where you rescue Ryuzi and Chihiro in the demon route. Lv2 mud-girls can be found in most routes, but there is a mob in the demon route map where you capture Rufadiel with 4 of them in one deck.

Ryuka Flames are really hard to find, but can't be captured until Syuya is at level F. There are 2 in a mob in the angel route in the map where you rescue Atori. Others may be found by battling level 5 bosses marked by exclamation points.

Alchemy Skills
Alchemy skills are listed under a character profile and upgrade as a character levels up. As they upgrade you become able to create higher level cards of the related type.