So I think splitting Concentration into two things might be worthwhile.
Focus is a medium or long-term high-value effect. You get 1 Focus at a time.
Concentration is something that can be disrupted from damage. When you have Focus on an effect, you also are maintaining Concentration: but spells can be Concentration without using Focus.
The point of this split is to break the "counterplay" from the "stacking" problem. I really like counterplay - the wizard is using magic to interfere with the barbarian? Well, knock the wizard down and the barbarian is free. That is concentration.
Focus, on the other hand, exists in order to prevent "I cast Haste and Dragon's Breath and Magic Weapon and Holy Weapon and Tenser's Transformation and Spiritual Guardians, then I step into the room and boom everything dies" and similar issues.
Buff spells, like Haste, are fun if they are impactful - but if they stack and are impactful, then pre-buffing is stupidly optimal. Instead, I want to encourage the use of Haste during combat; this makes its action cost also matter a bunch (as opposed to pre-buffing where it does not).
It is part of the anti-christmas-tree effect of attunement items; too many optimization points breaks D&D.
Concentration could even be assumed. Any time you have cast a spell with a duration, you have to make concentration checks or the spell gets disrupted. Only a few spells would be concentration-free.
Focus is a medium or long-term high-value effect. You get 1 Focus at a time.
Concentration is something that can be disrupted from damage. When you have Focus on an effect, you also are maintaining Concentration: but spells can be Concentration without using Focus.
The point of this split is to break the "counterplay" from the "stacking" problem. I really like counterplay - the wizard is using magic to interfere with the barbarian? Well, knock the wizard down and the barbarian is free. That is concentration.
Focus, on the other hand, exists in order to prevent "I cast Haste and Dragon's Breath and Magic Weapon and Holy Weapon and Tenser's Transformation and Spiritual Guardians, then I step into the room and boom everything dies" and similar issues.
Buff spells, like Haste, are fun if they are impactful - but if they stack and are impactful, then pre-buffing is stupidly optimal. Instead, I want to encourage the use of Haste during combat; this makes its action cost also matter a bunch (as opposed to pre-buffing where it does not).
It is part of the anti-christmas-tree effect of attunement items; too many optimization points breaks D&D.
Concentration could even be assumed. Any time you have cast a spell with a duration, you have to make concentration checks or the spell gets disrupted. Only a few spells would be concentration-free.