To upgrade an Artifact of rarity N to N+1 you need to sacrifice 4 other artifacts of rarity N.

I got the idea of using the rarity as a value, and to upgrade a card you need to sacrifice 4*N worth of artifacts. (N = rarity of card you are upgrading)

Poor artifacts have a value of 1, while Legendary artifacts have a value of 6. The artifacts from multiple types could be combined in this way.

This means that you can upgrade a card from Poor to Common using a single Rare artifact, or 2 Poor + 1 Common. You could also upgrade and Epic artifact to Legendary by sacrificing 25 Poor artifacts.

Let me know your thoughts!

sounds promising

If such a system existed in Diablo II it would be so easy to grind top gems! :D
You can't give a "upgrade to legendary with 25 poors" because in the shop you can buy 25 poors with 500 coins, and buying legendary costs 4860 coins.
So this idea probably will never become live.

Though, the idea "upgrade low level using a higher level" is fine! But upgrading high level with low level is dead. imho

5 poor give one common, so 25 poor are needed for 1 uncommon etc. So for upgrading an epic to a legendary artifact you need 4 sacrifical epic artifacts additional to the one you want to upgrade. An epic artefact is worth 625 poor artifacts (if i didn't miss one rarity step), so overall you'd need 2500 poor artifacts as sacrifice to upgrade an epic to a legendary artifact.

That being said, it might make a lot more sense to buy several epic artifacts to upgrade the one you actually want later than gambling on legendary artifacts directly if you buy them with coins

Edited 11/11/2020 18:19:27

Maybe it should be limited to only the current tier of the artifact you are upgrading and higher, so you can just use less than 4 artifacts when upgrading

The values aren't from 1 (poor) to 6 (legendary); rather the values are 1 - 5 - 25 - 125 - 625 - 3125, and even this doesn't take into account that 12 hours are needed to upgrade an artefact to the next tier. If we assign a value of 1 for the time required to upgrade, then the value list looks like 1 - 6 - 31 - 156 - 781 - 3906.
Using a large number of lower tier artefacts to upgrade a current tier artefact is a no-no. The players should first upgrade those to current tier, then use them to upgrade their preferred artefact.
There's a merit to the proposal of using a higher tiered artefact for upgrades. Let's say you have a useful uncommon artefact, and a rare one you don't need. Upgrading the uncommon to rare requires 4 other uncommon artefacts; it would be nice if you could use the rare artefact (that is worth at least 5 uncommons) in place of the currently required 4 uncommons. However an "abuse" of this feature might take place: let's say you have only needed artefacts, that you don't want to sacrifice, and are willing to buy artefacts with coins. Buying 4 uncommons cost 4*180 = 720 coins. One could buy a rare for 540, and use it to upgrade his uncommon.
Maybe it's better leaving the current system as is.

Yes, using the lower tiers was an oversight on my part....

To fix the workout with buying artifacts, a penalty of -50% could be used to if an artifact of a higher tier is used, so that it would be 4 of the same tier, or 2 of a higher tier.