There is a comparative dearth of ritual spells in D&D5.
On the way home from work the other day I was thinking what would happen if any spell could be done as a ritual. Higher level spells would simply take longer.
yes, I do a lot of my noodling while driving. Oddly enough, I have not yet crashed or gotten at ticket, despite driving a WRX. Go figure)
Even the Ritual Master Feat only allows you to cast spells with the Ritual tag.
Anyway, here’s the thought. You never want a ritual, even for a 9th level spell, to last longer than it would take to simply cast it and then take a long rest. You probably don’t even want to come close to that. So 4-6 hours to cast a 9th level spell as a ritual is probably as much as you’d want to go. Even 1-4 hours for that upper limit might be pushing it.
On the low end, casting a spell as a ritual usually adds 10min to the duration to cast. So the minimum time to cast anything as a ritual, even for a 1st level spell, should probably be 10min – maybe a bit longer because this doesn’t seek to overwrite the ritual tag, merely supplement. Let’s say 20min is the lower end.
That would make a time-to-cast chart look like this, with entries for “fast progression” and “slow progression.” I’m assuming a geometric progression, so each level is X times slower than the level before.
|Slow Cast||Fast Cast|
|6||2 hours||1 hour|
|7||3 hours||1 hr 15 min|
|8||4 hours||1.5 hours|
|9||6 hours||2 hours|