I've found that the explanation for The Ring of the Sun Princess has been a little confusing, and for that we have to thank the in-game item description. "Boosting" miracle synergy is its less common, secondary use. A better explanation for the RotSP would be that it "gives" miracle synergy.
What do I mean by that? When you're wearing the ring, just imagine an invisible, permanent resonance sign following you around. That's pretty much all it does. Using a synergy-capable miracle with the ring on is no different than not wearing the ring and using the same miracle standing near a resonance sign. They do the same thing, with the same degree of effect.
The only time a miracle synergy gets boosted, is when the ring stacks with a resonance sign. Two nearby resonance signs do not stack, but the ring + a resonance sign do stack. There is a visual difference, the white ring that appears over your miracle's icon will appear thicker for what I call the "double synergy boost".
A couple other misconceptions:
-Unlike Force, Wrath of the Gods does not have its ranged increased.
-All resonance signs are the same and always boost ALL synergy-capable miracles. Earlier speculation by some believed that resonance signs corresponded with different groups of miracles, giving boosts to some but not others (force and wotg vs. heal and replenishment). Instead, there are 9 total that will always receive the boost, and the rest will not.
Here are my findings copy/pasted:
Miracle Synergy Indication (The White Circle on your Miracle's Icon)
- When a miracle displays a glowing white circle over its icon, it has received a synergy boost that will work upon use. For those who aren't wearing the Ring of the Sun Princess, this can only be activated by standing near a miracle resonance sign.
- The Ring of the Sun Princess has a built-in synergy boost. While worn, all miracles than can be synergized will be treated as if there's a permanent miracle resonance sign nearby.
- If someone who is already wearing the Ring of the Sun Princess approaches a resonance sign, the effect will stack as a double boost and create a thicker white circle over the icon.
^ Photo. The difference may appear subtle between the two pictures, but it's an obvious difference when seeing the thick version activate/ deactivate in the game. The thick, double boost also has white speckles around it.
- The white circles can be difficult to see if a talisman is equipped and the miracle is able to be cast at the moment. Put the talisman away to see the synergy-indication circle clearly.
Ring and Synergy Damage Boosts
- Synergy and double synergy boosts will stack with extra damage created by items like the Ring of the Sun's Firstborn.
- The double boost is created only by stacking a resonance sign with the Ring of the Sun Princess. Two nearby resonance signs without the ring will not create the double boost.
Synergy Capable Miracles
- Heal
- Great Heal Excerpt
- Great Heal
- Replenishment
- Force
- Wrath of the Gods
- Emit Force
- Soothing Sunlight
- Bountiful Sunlight
Incapable: Magic Barrier, Homeward, Seek Guidance, Vow of Silence, Tranquil Walk of Peace, Lightning Spear, Great Lighting Spear, Darkmoon Blade, Gravelord Sword Dance, Gravelord Greatsword Dance. Unlikely, but not yet tested: Great Magic Barrier, Sunlight Spear.
Miracle Synergy boosts different miracles by different amounts
- Heal: ~8.3% more health restored w/ boost. ~16.6% w/ double boost.
- Replenishment: 20% faster/ more health w/ boost, 40% w/ double boost.
- Force: Range is increased by ~2-3 feet.
- Wrath of the Gods: No range increase. ~4.5% more damage w/ boost, ~9% more damage w/ double boost.
- Emit Force: ~5% more damage w/ boost, ~10% more damage w/ double boost.
- Bountiful Sunlight: Same improvements as Replenishment.
- Unable to test Great Heal Excerpt, Great Heal, and Soothing Sunlight yet.
Not all of these numbers are exact and will vary slightly. You can expect results that are a couple 10ths of a percent off.