Sorcery Keystone Concept: Eldritch Study [Revised]

Here’s a revised version of my keystone concept, based on feedback I got.

The fantasy of this keystone is a scaling/utility rune, where you practice casting your spells, slowly getting better and better, until you unlock their full potential. It takes a lot of effort, but the payoff is potent.

Eldritch Study

• For every 65 mana (+30 per Practice stack) spent on an ability, that ability gains a Practice stack (max. 10, requires 2000 total mana spent to max one ability). Abilities with 10 Practice stacks are considered Mastered. Only 50% of the mana spent on abilities that affect minions (but not champions) counts. Only 10% of the mana spent on abilities that do not affect minions or champions counts.
• For each Practice stack an ability has, it gains 1% cooldown reduction, and 1% of the mana spent to cast it is refunded.
• Whenever you cast a Mastered ability, you gain a shield equal to 20-60 + (30% bAD) + (20% AP) which decays over 3 seconds after that ability's cast/channel time. Subsequent casts refresh the shield (they don't stack).
• Other allied champions affected by a Mastered ability also gain this shield.
• Enemy champions affected by a Mastered ability take magic damage equal to 10-40 + (15% bAD) + (10% AP) over 1 second. Subsequent hits refresh the duration (they don’t stack).
• Per-cast, per-target cooldown of the shield/damage is 4 seconds (e.g., Swain’s ult wouldn’t constantly apply the DoT to all enemies in range, but it would reapply the damage to every enemy champion in range once every 4 seconds. However, if he landed all four of his abilities in quick succession, all targets would be afflicted with the keystone damage four times. Another example, on a spammable cooldown like Karthus Q, each individual cast would apply the DoT, even though they happened within four seconds of each other.)
• While in the fountain and for 10 seconds after leaving it, you cannot gain progress towards Practice stacks. This debuff ends early if you enter champion combat.

Compared to the previous version, the keystone now requires you to actually hit something to get a meaningful amount of progress, and stacking in or near the fountain simply doesn’t work. Using your abilities to fight enemy champions would be the fastest way to stack it, although using abilities for waveclear does give you some progress.

This version has the threshold for getting a Practice stack go up for each Practice stack that ability has. It’s relatively easy to get the first few stacks, but it takes more and more mana to keep getting stacks. This way, you can still get the minor benefits from the keystone rather early, but Mastering an ability is pushed far later into the game.

Practice stacks would be counted as the criteria is met. For example, Jhin’s ult. He activates the ult, immediately gaining 10% of the mana cost as Practice stack progress. He fires a shot, and hits a bunch of minions, gaining 40% of the mana cost as Practice stack progress (bringing him to 50% total). With the next shot, he hits a champion, and gains an additional 50% of the mana cost, for a full 100%. The third and fourth shots don’t add any extra progress, since all the criteria was met. Another Jhin example: His traps. They would provide 10% of the cost immediately when placed, which would then jump up to 50% as soon as they slowed/damaged a minion, then the full 100% when they slowed/damaged a champion.

For toggled abilities that constantly consume mana, such as Singed’s Q, the stack progress would count for as long as the criteria is met. If Singed just has it on and is hitting nothing, then only 10% of the mana he’s spending is going towards Practice stacks. Once he applies the DoT to minions, he would start getting 50% of the mana spent as progress for as long as minions are taking damage. The same would be true for getting 100% progress for as long as the ability is damaging champions.