Helldritch
Hero
That's a great houserule, Helldritch, but please don't confuse people looking for RAW answers.
Sent from my C6603 using EN World mobile app
So you say.
Remember: Specific beats out the general rule.
Nothing prevents you from using your reaction in the rule. You can not cast a spell when you cast a bonus action spell unless it is a cantrip with a casting time of one action. Shield and counterspell are reaction spells. They are not action spells. They do not use your "action" when you cast them. I really do not see the "house ruling" in there.
The intent of the rule is to prevent the double fireball, lightning bold, Ice storm etc.. with the sorcerer's ability of transforming an action spell into a bonus action spell. Action, Bonus action and Reaction are independant of each other.
A reaction is specific, it responds to a triggering event which does not happen all the time. In fact you can't take a reaction if there is no triggering event because you have nothing to react to. Because of the triggering requirement, you can't even cast shield as a prevention, you need to be victim of an attack or be targetted by a magic missile spell. You can't counterspell without having a spell to counter etc...
Specific beats out the general rule.
I.E. From sage advice
Can a bonus action be used as an action or vice versa? For example, can a bard use a bonus action to grant a Bardic Inspiration die and an action to cast healing word?
No. Actions and bonus actions aren’t interchangeable. In the example, the bard could use Bardic Inspiration or healing word on a turn, not both.
The same holds true for reaction.
It is unfortunate that the example on counter spell does not include this scenario
A sorcer cast a cantrip (fire bolt)
Then transform a fire ball into a bonus action spell.
Ennemy caster cast counter spell.
Can the sorcer counter the counter the counter spell?
I'd say yes. I believe that it is both raw and rai.
I wonder what WotC would say...