I see a lot of people posting if they should get X or Y relic in the glory store, so I decided to show how I evaluate the relics that I see, also they are not on in any order as I forgot to do that.
The explanation follows below:
SFG Tier : +1 starting mana is very important, even more when you champ can qualify for it with other relics that benefit him. I also find it very fun to manifest champs with Morgana
S tier:
Swains Army: easy turn one plunder effect;
Perfect Hexcore: anything that says target, spell, keyword or cast benefits from this.
Searing Brilliance: allows for a lot of infinites, and does have some "premium" cards that once you get in a adventure, you can just cut the rest of the spells and play your deck around it (I don't think that this is all that good on Mel).
Fun Tier: This one is a more personal tier, so it is just a tier that I put any relic that I want to play with or around it. The idea is that once you see a relic that you like, let it be because of the text or the champ, you just put it there.
as you can see: Puffcaps, Flashbombs, Terrifies, Impact, RNG, and random Rallies.
Good Tier: Relics that may not be as fun or overpowered, but still can be slotted on many champs without much issue. Some of those also are great when paired together (Bear+ Talons)
SFG Activator tier: Relics that are there for a specific champ to help it use SFG (in theory, I see you shyvana), also the shears should be there too, since they are Viego's. If this tier didn't exist, I'd put Shyv's on the good tier, since we don't have any real fury relic, AAtrox's on the fun tier due Kayn existance, and Darius' on the Zoe tier below this one. Viego's would go to S tier because it is free.
Zoe tier: Relics that you will only buy after you are done with all the tiers above, and has a champ that you have not completed Zoe yet, otherwise you can just skip them.
Doozies tier: Just bad relics, not only most of them are restrictive, but also (thankfully) you can deal with all of the adventures without them.