In a recent game, one of my players (Warlock, Celestial Patron) taken Pact of the Tome. Whilst we were in a dungeon, he ritually cast Unseen Servant.
We were unsure if this was possible and so consulted the PHB. The glossary stated:
If you have a spell prepared that has the Ritual tag, you can cast that spell as a Ritual. The Ritual version of a spell takes 10 minutes longer to cast than normal. It also doesn’t expend a spell slot, which means the ritual version of a spell can’t be cast at a higher level. See also chapter 7.
When we looked at Chapter 7, it states:
Rituals. Certain spells have the Ritual tag in the Casting Time entry [...] To cast a spell as a Ritual, a spellcaster must have it prepared.
This was not very clear to me, so now I am just checking, as Pact of the Tome states:
Cantrips and Rituals. [...] and choose two level 1 spells that have the Ritual tag [...] you have the chosen spells prepared, and they function as Warlock spells for you.
There is nothing on the Warlock page that outright says they can ritually cast any spell with the ritual tag, though Chapter 7 and the Glossary would. As such I am looking to mainly confirm: Can Warlocks cast spells as a Ritual with Pact of the Tome?
Moreover, due to the wording of Chapter 7 and the Glossary: Can any spell caster cast any ritual spell as a ritual?