I must say, I am a huge fan of the ring and would love to see a hardmode and post-cultist/pillars version of it! IF your looking for ideas for new items a andnd im not overstepping my bounds, I have some things that other mod's don't deliver I would love to see more of. So here goes;
1: Celestial Signet [Accessory]
Recipe: Pulsar Band + Celestial Stone.
Place: Crystal Ball
Effect: Gives 15 Armor Penetration, +20 Max Mana, +moderate mana regeneration, in addition to the full effects of a Celestial Stone, which is seen here;
https://terraria.wiki.gg/Celestial_Stone
Reasoning: This helps every class/build/role - magic, summon, melee, throw, ranged, and mod-damage types like Healer/Radiant, Bard/Symphonic, and Alchemist/Alchemical damage types from Thorium and Tremor mods, respectfully, and is a nice mid/late game upgraded to the Pulsar Band.
2: Titanic Emblem [Accessory]
Recipe: Any 3 Different Class Emblems + Titan Glove.
Place: Tinker Table
Effect: Gives +10% all damage and +100% to all knockback.
Reasoning: Not enough knockback items in the game to make it worth investing in as a stat in my personal opinion, and worse of all, its usually only tied to melee accessories, making it a "non-factor/thought of stat" for most of builds. Though its nice to have, nobody really wants to waste a valuable accessory slot on it. Well now: its worth a slot for hardmode.
3: Frenzy Shard [Accessory]
Recipe: Anklet of the Wind + Aglet + Feral Claws + Nature's Gift + 1 Crystal
Place: Crystal Ball
Effect: Gives +15% movement speed, +15% to all attack/cast/firing speeds, and 15% mana cost reduction and 15% chance not to consume ammo, and +15% velocity on all projectile attacks [ranged, castng, etc].
Reasoning: Like knockback, attack speed is rarely utilized over raw damage except for a handful of builds, and the few times it comes up, its almost a melee-exclusive stat option (feral claws, mechanical gloves, fire gauntlet, etc). This gives people a nice early hardmode item for a chunky bit of attack speed with other stats to utilize that type of gameplay for any class (except summoners. Sadly.)
4: Void Signet [Accessory]
Recipe: Pulsar Signet + Destroyer Emblem + 25 Stellar Fragments + 25 Solar Fragments + 25 Stardust Fragments + 25 Vortex Fragments + 5 Luminite Bars
Place: Matter Manipulator
Effect: Gives 30 Armor Penetration, +40 Max Mana, +high mana regeneration, the full effects of a Celestial Stone, in addition to +10% more to all damage types [20% total with celestial stone benefits] and +8% more crit chance [10% total with celestial stone benefits].
Reasoning: The end-game finale to pulsar band's humble beginnings. A force of reckoning for any build. I mean, post moonlord, it doesn't really need to be balanced, you know?
5: Storm Emblem [Accessory]
Recipe: Titanic Emblem + Storm Shard.
Place: Matter Manipulator
Effect: Gives +8% all damage, +100% to all knockback, +15% movement speed, +15% to all attack/cast/firing speeds, 15% mana cost reductions and 15% chance not to consume ammo, and +15% velocity of projectiles.
Reasoning: Effectively a post-cultist item for attack speed and/or knockback builds of any role - melee, ranged, caster and even summoner to a slight degree. Not very useful against moonlord at this point, but, at least its available.
6: Sword Storm [Weapon; Magic]
Recipe: Razorblade Typhoon + Sword Bible + Frenzy Shard
Place: Crystal Ball
Effect: Damage 45 [Magic], Knockback 8 [Average], Mana 14, Critical Chance 8%, Use Time 8 [Insanely Fast]. Effectively identical to the spell Razorblade Tryphoon found here;
https://terraria.wiki.gg/Razorblade_Typhoon#/search except that you fire a barrage of insanely fast, piercing, bouncing, circular clusters of swords or sawblades that have less base damage (but over twice the cast speed) per shot, has a slightly higher crit chance and knockback over Razorblade Tryphoon, and a slightly reduced mana cost to make up for the insane speed.
Reasoning: Basically a great post fishron weapon to use for fights leading up to moonlord, and beyond when used with Storm Emblem AND Void Signet for the increased attack/cast speed, flat armor penetration, and reduced mana cost.
Well, thats all I can think of for now. Whatcha think?