Yup, I took the time to see what the benefits of the various combinations of Earrings and Hero Rings for magic attacks and Atlas Armlets versus Hero Rings are. Below, you'll find the results. (If anyone wants to see the details, I've attached the spreadsheet to this post.)
MAGIC TEST
Test Environment: I used Fire for my magic test on Tyranosaurs. I cast Fire ten times and used the average damage from those ten spells to determine the increase each Relic combination gave.
Magic Attack Results
Avg Damage Increase No Relics 3204 1 Earring 3929 23% 2 Earrings 4782 49% 1 Hero Ring 3857 20% 2 Hero Rings 4797 50% 1 Earring &
1 Hero Ring4727 48%
Based on my tests, equipping one Earring will give you roughly a 25% boost in magic damage, while two Earrings will give you double that with roughly a 50% boost in magic damage. While using Hero Rings, having one ring equipped offers roughly a 20% boost in magic damage while equipping two takes you up to roughly a 50% boost in magic damage.
Magic Attack Summary: The boost to magic damage seems to be capped at 50%. Based solely on magic attacks, if you're going to equip one Relic, a single Earring is the better choice as it gives 5% more magic damage than the single Hero Ring. If you're equipping two relics, then it doesn't really matter as any combination boosts magic damage by roughly 50%.
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PHYSICAL ATTACK TEST
Test Environment: I attacked Tyranosaurs with a Dagger for my physical test. I attacked ten times and used the average damage from those ten attacks to determine the increase each Relic combination gave.
Physical Attack Results
Avg Damage Increase No Relics 3305 1 Hero Ring 4244 28% 2 Hero Rings 4216 28% 1 Atlas Armlet 4081 23% 2 Atlas Armlets 4260 29% 1 Hero Ring & 1 Atlas Armlet 4224 28%
Based on my tests, equipping one Atlas Armlet will give you roughly a 25% boost in physical damage. Equipping two Atlas Armlets, one or two Hero Rings or one Hero Ring and one Atlas Armlet will give you roughly a 30% boost in physical damage.
Physical Attack Summary: The boost to magic damage seems to be capped at 30%. Based solely on physical attacks, equipping one Hero Ring is the way to go as there's no benefit to equipping anothe relic in combination with it as the phyiscal attack damage cap is already reached. Earlier in the game, the Atlas Armlet will work well, but once you find the first Hero Ring you hit the phyiscal damage boost cap and there's no need for another relic.
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SUMMARY - Putting is all together
In looking at the results of the two types of test, the clear winner in raw damage appears to be two Hero Rings. It gives you a 50% boost to magic damage and a 30% boost to damage. If you want to free up a relic spot for something else, a single Hero Ring still gives you a 20% magic and 30% physical damage boost. But if you're solely intersted in magic damage, the Earrings are the better way to go. They perform as well or better than the Hero Rings for magic damage boosting and you receive them earlier in the game. Plus, by equipping Earrings you leave the Hero Rings free for others who might need the physical damage boost. As for the physical damage boost, one Atlas Armlet earlier in the game and one Hero Ring once you find it will take care of all of your needs, as equpping a second Relic for damage output doesn't really do anything.
Phew, that was intense, yet fun. I hope it helps!