So, we're back at it and this time covering the additional layer of design that wasn't covered in the previous post. A better designer would probably have started smaller and then made each of the items created grow stronger. That might be one of the lessons learned from this, because after a few sessions of having them in play...they are a bit strong! There's nothing wrong with powerful items in theory, but it's starting to feel like some of the party members are missing out on being able to do Cool Stuff(TM). Let's go over the design, and it'll become a bit more obvious what went astray.
The Initial Idea
As I mentioned previously, the items are part of a set. The items individually do have their own enchantments, and then an additional "enchantment" in the form of the blessing. Since this was a set of items given to the order of paladins, I thought it'd be a good incentive to actually use all of the items. What I didn't want to happen was just for them to be given to the other players. Part of this was solved by just making some of them require attunement. The restriction on who can attune to it worked well, but not all the items required attunement. Still, using all the items at once conferring a bump to the previous enchantments sounded good.
The Method
First things first: How do I actually make it so that all three items have to be used in order for the player to benefit from the set bonus? The first thing that came to mind for me was to just label them as a set, and in that label describe the effects of having all of them on. That would work initially, but it meant that each one would have an additional block of text at the bottom. It works in games like Diablo when you have UI elements that allow you to see much more of the detail for an item. In Roll20, that's not very easy. It'd otherwise require additional features/traits for reminders. Then there's the idea that if one item is missing the entire set stops functioning. That would suck, especially if, say, one item was stolen. Not that I'd do that to my players.... Still, the thinking led me down that road, and I came up with essentially a set bonus:
Dawnblade Regalia While you are thrice Blessed by X. Your item feature improves by Y
That was the basic idea I had, and so far it made sense to me. Each item is blessed, while you have all three items you get a bonus. It also means that if the player unattunes or otherwise loses a blessing, all of the extra powers stop working. This means each bonus has to be just that, a bonus. If it's too empowering then the removal feels too much like a robbery. With that in mind, I went back over each item to figure out exactly what that bonus would be.
The Details
After looking over the items in their near-final state, I decided to make sure each had the complete fantasy of what I set out to convey with each item. That made it easy for some, and a tad harder for others. For example, the horn normally summons a dragon, its blessed ability lets you heal allies with Lay on hands. Yet it did not fully deliver on the fantasy of a rallying cry with these two abilities.
I could have made the dragon gain an additional effect. That was less exciting. I decided instead to steal a page from the Fighter's book of tricks. The battlemaster can give free movement/attacks to others with their superiority dice. So instead, I worked in something similar.
The Horn
Roar of the Sun: Those that are healed by this effect can move up to their speed and make one weapon attack against a hostile creature, dealing extra radiant damage equal to the number of hit points they regained.
Now, some of you can already see my mistake. Indeed, I missed it initially and we played a few games with the items. The effect only came up recently, and not even in the manner that is obviously very unbalanced in hindsight. The party is now 14th level, and a 14th level paladin has 70 HP in their Lay on Hands pool. The item recharges once per day, and the party is 5 characters strong. That's 350 Hit points worth of damage if they all hit. Being able to delete a dragon in one turn is waaaay too strong.
So, now that I've realized my folly, I have adjusted it:
Roar of the Sun:Those that are healed by this effect can move up to their speed and make one weapon attack against a hostile creature, and gains a bonus to attack and damage equal to your Charisma modifier.
Now it's an order of magnitude less powerful. Still strong! The bonus to hit though means that those that normally don't depend on weapon attacks can hit something, and still do some damage. Even if only the characters that typically do use weapons attack, it's still a great benefit.
The Sword
For the sword, the idea of dive-bombing the enemy like a dragon dropping from the sky seemed really cool to me, and I know it'd be appealing to the player as well. Not to mention I had spent a deent amount of time listening to one Lit-RPG with a character with such an ability. The sword itself didn't allow for that, but the armor and sword made for the combo all on its own. That left the armor itself for a bonus.
Sun Dragon's Wrath: If the attack is made while airbone and from maximum range, the attack deals an extra 4d12 radiant damage, and the foe must make a DC 20 Strength save or be knocked prone.
Is the 4d12 on top of the 4d12 from the sword a lot? Probably. But it's one attack, and being knocked prone with flanking already as an option is not that huge.
The armor
The armor was probably both the easiest and hardest. I could have simply increased the flight time, or flight capabilities of the base armor. I could have increased the range of an aura, or adjusted the effect of the savior mechanic I made. In the end I sort of punted. Knowing full well that automatically failing a save might take the Paladin out of the fight (which is dramatic!), but might also just outright kill them (which is not!) I hedged my bets.
Immortal Dragon's Blood: If after suffering the effects of the failed saving throw would bring you to 0 hit points,or kill you, you drop to 1 hit point instead.
Simple, and it prevents some edge cases. This wouldn't prevent the paladin from then getting hit by a second effect that would kill them, but that's true of any death-defying effects (e.g. Death Ward)