In Genshin Impact artifacts are what will be your armor slots in a typical RPG and also one of your main source of stats.
Each artifact belongs to a set and each set has 2 set bonuses at 2 artifacts and 4 artifacts of the same set. There are currently 5 artifact slots and 5 types of artifacts and each can only be equipped to their corresponding slot. Each artifact has main stat and up to 4 maximum secondary stats depending on level.
Every 4 levels of the artifact you start unlocking new secondary stats up to 4 stats. After you?ve unlocked all 4 stats you start upgrading them randomly as well, an upgrade basically doubles the effect (I?m not sure about the formula) of a secondary stat. This is one of the reasons why the higher the rarity the better since you can get more upgrades on the stats as well. The main stat of an artifact scales with level but the secondary stats can only get upgraded every 4 levels.
Also unlike weapons you can only level artifacts using other artifacts and you also get a?15% experience penalty?for using a leveled artifact to level another artifact. Depending on the rarity of the artifact it starts out with a different number of secondary stats, 3* start with 1, 4* with 2 and 5* with 4. Also they have a different level cap, up to level 20 for 5* artifacts.
Flower of Life (Flower): These artifacts always have HP as their main stat. This is the least important slot for most characters.
Plume of Death (Feather): These artifacts always have Flat ATK as their main stat. This is the most important slot for most characters.
Sands of Eon (Hourglass): see below
Goblet of Eonothem (Goblet/Cup): see below
Circlet of Logos (Head): see below
What do you want on an Artifact?
Since most of the stats are random this begs the question, which stats you need? Obviously this depends on many factors as it is a complex topic but I?ll try to make it as simple as possible. Keep in mind that there are some quirky characters (Noelle for example which scales with DEF) which scale differently than most so keep that in mind.
For the secondary stats, generally speaking, you always want to have?% ATK (early game) / Flat ATK (early game, also I?ve only ever seen it on Flowers?) / Elemental Mastery (late game) / % CRIT Rate (late game) / % CRIT DMG (Late game)?as a secondary stat. Early on I?d say you should prioritize the ones with % ATK because they help you the most, later on you?d want the other stats because they scale better but as many as you can get the better, of course you shouldn?t avoid an artifact because it doesn?t have all of these 4 stats since it?s quite likely that you won?t get as lucky for it but at the same time keep in mind that unlike weapons, 5* artifacts are always better than 4* artifacts and bellow, so don?t stress out too much on that because anyway most of them will end up as experience for 5* artifacts, there you can go into farm hell for the best secondary stat rolls until we get a way to reroll the stats ourselves. (which will most likely come later on, but we?re probably talking 6 months or even a 1 year into the game)
For the main stats on the Hourglass, Cup and Head, the story is pretty similar except here there are some other stats which can appear. For example you can get % Hydro DMG which would be good on Mona. Early on if you get any 3* or higher artifact with % ATK as a main stat, level it up since it will help you quite a lot, even more so than sets.
Which set bonuses should I watch out for?
Early on I?d say any set with gives you % ATK, Elemental Mastery and % CRIT for example the Resolution of Sojourner, the Instructor and the Berserker sets early on. There?s also the Gladiator set from the Get Ready for The Road Event which is also decent.
Which should I prioritize, set bonuses or good rolls?
As with all the situations, it depends, but sometimes you can easily figure it out. If your Berserker set doesn?t have any % ATK main stat rolls but you have some other random pieces which do, I?d say use those because for example a 4* artifact with a % ATK main stat will have around 20% ATK at level 8 (which is really easy to get) and this obviously beats most of the set bonuses you can get even.
Generally speaking I?d say it?s like this:
Main Stat > Set Bonuses > Rarity > Secondary Stats?for the early game at least. Later on I can?t really say right now, we will wait and see.
How much should I level them?
Since you will get only a 15% experience penalty when using the artifact to level up another one you shouldn?t be too mindful but I?d say don?t invest into 2* artifacts at all since you will get a lot of 3* artifacts pretty fast. Keep in mind that as you progress you will end up needing 2 teams, which means at least 20 decent artifact setups (2 Main DPS and 2 Burst Support) so don?t just use everything up to make a few strong artifacts.
I?d say go up to level 12 for Feathers (if it?s a 4* with good secondary stats you can max it at level 16 even) and 8 for the rest until you have enough of them with decent stat rolls for 2 teams. Also you shouldn?t bother leveling up Flower Artifacts unless they have good secondary stats, a good set and you?re willing to pray to the RNG gods to get upgrades on the good stats and not the bad ones.
Artifacts are your armor slots in this type of RPG and they?re also your main sources of stats, early game prioritize % ATK over the other offensive stats, the Main Stat is more important than everything else early on, level them up to 12, especially feathers, until you get enough good stat rolls for 2 team, then you can even max them if you want but don?t level Flowers unless they have good secondary stats and a good set and generally invest only in 3* artifacts or higher.