I play a bard and my party wants me to learn the spell Leomund's Tiny Hut (or Tiny Hut for those without the full access to D&D Beyond). That spell is tagged as ritual, and before agreeing to take that spell, I want to be sure of the way of using it.
As a DM, I've never used rituals and I've never disallowed my players to cast rituals, also I never was under the impression they cheated about it. However, here in the game where I play a bard, the DM plays exclusively by the rules. So I better get my stuff straight.
The Bard's spellcasting ability says:
You can cast any bard spell you know as a ritual if that spell has the ritual tag.
So that means I can cast Leomund's Tiny Hut as a ritual since it's tagged with ritual.
The whole rule about rituals is the following:
Certain spells have a special tag: ritual. Such a spell can be cast following the normal rules for spellcasting, or the spell can be cast 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.
To cast a spell as a ritual, a spellcaster must have a feature that grants the ability to do so. The cleric and the druid, for example, have such a feature. The caster must also have the spell prepared or on his or her list of spells known, unless the character's ritual feature specifies otherwise, as the wizard's does.
If I understand well, I have two possibilities to cast Leomund's Tiny Hut as a ritual: either spend 10 minutes and 6 seconds, or spend 6 seconds and a spell slot, correct?
If I cast the spell as a ritual, I don't expend a spell slot, but does that mean that I'm not required to have a free spell slot? In other words, if I've used all my level 3+ spell slots, can I still cast it as a ritual?
Conversely, if I want to cast it ASAP, can I cast it with a level 4+ spell slot? The sentence "the ritual version of a spell can't be cast at a higher level" makes me doubt...
Finally, can I voluntarily interrupt my ritual casting? If the situation becomes dangerous or otherwise?