Casting multiple spells simultaneously! (not really)
Requiring the caster to ready the spell every turn doesn't seem logical to me. They readied the spell by casting it (and expending a spell slot) with a clearly stated trigger, and now they must use their single concentration "slot" to hold the spell in a readied "reaction" state. The spell is effectively wasted if the trigger never happens, the caster fails a concentration check, casts another spell using concentration, or if they have no reaction when the trigger happens (yes, shield, I'm looking at you). Concentration rules already limit what the caster can do while concentrating on a spell. I see no reason in the rules or otherwise to tack on more limitations for a readied spell.
And... back on topic... I was initially concerned about the non-proficient saving throw weakness when I first read through the rules... However, the more I play the game, the more I appreciate the elegance of the concentration mechanic in 5e. Concentration is a wonderful limiting mechanic to bring casters back down to the same playing field as the martial classes. This is one of my favorite mechanics in the new rules.
Hmm.
That makes me think of something that seems to work under the rules:
Readying a spell requires concentration. Once you have done so, the spell is in one of your hands, held so that it is not cast. You can trigger the spell with a reaction based on the trigger you previously specified. I'd rule that you can also release the spell by using your action, on your turn. Because anything else wouldn't make sense.
So, you're now using your Concentration on the spell in one of your hands. As long as you continue concentrating (I think the maximum is always ten minutes), you're holding that spell.
So what stops you, next round, from casting a new spell?
If the new spell required concentration, then you lose the readied spell. You also can't cast it at all if you're holding something in both hands - so if the previous spell is in one hand, you'd have to drop or stow whatever is in the other. However, as long as you maintain concentration on the readied spell, it would still be there.
You would, by the rules, lose your readied
trigger unless you spent an action on your turn to ready the trigger again. You also still couldn't release the readied spell
and cast a (non bonus action) spell on your turn (the rules only state that you can use a reaction to trigger the readied spell; it makes sense that you could use your action, instead. However, there's no rules support for it being less than a reaction or action). You could cancel the readied spell for free, though.
Basically, this is an interpretation of the rules that doesn't would make for some really thematic roleplay, doesn't seem to be contradicted by any of the rules and doesn't actually break any of the assumptions of power.
Thoughts?