When do Druids gain the ability to cast each spell level?

I understand spells and that spell levels don’t correspond with character level but on this website it says:

Spell level and character level don’t correspond directly. Typically, a character has to be at least 17th level, not 9th level, to cast a 9th–level spell.

I understand this, but what character level is a Druid required to be to cast a spell at any given spell level?

Just to be clear, I am not asking about spell slots here.

Can Erupting Earth be cast somewhere that isn’t on “ground”?

The spell Erupting Earth says:

Choose a point you can see on the ground within range.

Does the use of the word "ground" limit this spell to floors that would be considered an "exposed surface of the earth"? Other possibilities include:

  1. An indoor room on an upper level or over a basement
  2. An outdoor deck or patio
  3. A raised platform like a stage or pulpit
  4. A roof
  5. A balcony

Related: Does the spell Erupting Earth disrupt the surface it’s cast on?

What is the class of a spell cast from a staff?

In D&D 5e when a character casts a spell from a staff (e.g. staff of a magi), what is the class of that spell? It is important for items like "+1 to DC for this class spells that you cast" from Tasha’s.

Specific example:

  • I am a lvl 20 Artificer.
  • I am attuned to and holding a Staff of Power, and casting Hold Monster from it.
  • I am also attuned and holding in my other hand (let’s say DM would allow my hand to hold all of them, this is just for illustration) all of the following:
    • +3 All purpose tool (bonus to artificer spells I cast).
    • +2 Arcane Grimoire (bonus to wizard spells I cast).
    • +1 Bloodwell Vial (bonus to sorcerer spells I cast).

What bonus to DC will I get from these items when casting this Hold Monster?

Healing Word in a Higher Level Slot — is it still a Bonus Action to cast?

If I prepare healing word in a higher level spell slot, is it still a Bonus Action to cast?

Related context

My DM cites Critical Role as evidence that this is probably not the case because in all the hours he’s watched them play their 5e campaign, they have ruled healing word in higher slots as not a Bonus action.

I’ve not watched Critical Role, so I don’t know if this is even the case in the show.

Protection from Evil cast on a player who’s already under a Charm Person spell?

I’m currently playing a D&D 3.5 campaign and in our last session our fighter has fallen under a Charm Person spell cast by an evil enemy spellcaster. My character is a Cleric and has access to both Protection from Evil and Magic Circle against Evil. If I cast the former upon the figher, or the other one so that the fighter is included in the affected area, what happens? I’m not sure how to interpret the spell’s description. From the PHB (emphasis mine):

The barrier blocks any attempt to possess the warded creature (by a magic jar attack, for example) or to exercise mental control over the creature (including enchantment (charm) effects and enchantment (compulsion) effects that grant the caster ongoing control over the subject, such as dominate person). The protection does not prevent such effects from targeting the protected creature, but it suppresses the effect for the duration of the protection from evil effect.

Therefore, it seems that once the spell is cast the target becomes immune to the mental influence of the evil entity. However, the spell description also says that (emphasis mine)

If the protection from evil effect ends before the effect granting mental control does, the would-be controller would then be able to mentally command the controlled creature. Likewise, the barrier keeps out a possessing life force but does not expel one if it is in place before the spell is cast.

It is clear that the spell does not nullify Charm Person, but the controller seems (at least) to be unable to give orders to the targeted creature. What about the order given before Protection from Evil is cast? There are three possible interpretations:

  1. Nothing happens, as the target was already Charmed before;
  2. The creature is still Charmed but the evil guy cannot give new orders (as Protection suppresses the effects of Charme);
  3. Charme Person is stopped for the duration of the Protection spell, and my fighter is free to act as he pleases.

Thank you for your input!

Does Astral Projection spell fail if cast while on the Elemental Planes or Material Echo Planes (Shadowfell, Feywild)?

Further to the question: Can there be portals in the Astral Plane that lead to the Elemental Planes , I wanted to ask does Astral Projection spell fail if cast while on the Elemental Planes or Material Echo Planes (Shadowfell, Feywild)?

According to the Etherealness spell (PHB p238) :

This spell has no effect if you cast it while you are on the Ethereal Plane or a plane that doesn’t border it, such as one of the Outer Planes.

According to the Astral Projection spell (PHB 215):

You and up to eight willing creatures within range project your astral bodies into the Astral Plane (the spell fails and casting is wasted if you are already on that plane).

And later in the same spell description:

Your astral form can freely travel through the Astral Plane and can pass through portals there to any other plane.

However, according to DMG in the description of relevant planar travel spells (DMG pg 46) it indicates the following :

And the astral projection spell lets adventurers project themselves into the Astral Plane and from there travel to the Outer Planes.

Accordingly, for both RAW and RAI, does Astral Projection spell fail if cast while on the Elemental Planes or Material Echo Planes (Shadowfell, Feywild)?

Can you Counterspell a spell cast using a Ring of Spell Storing?

Is a spell cast using a Ring of Spell Storing observable, in the sense that you could Counterspell it? Or is it essentially same as if you cast a spell using something like a Sorcerer’s Subtle Spell metamagic, or some other means of hiding or not needing the components of the spell? Does it maybe even depend on the type of spell, ie. if the spell effect is observable, it could be counterspelled, but not if there is no visible effect?

Relevant snippet from the ring description:

While wearing this ring, you can cast any spell stored in it. The spell uses the slot level, spell save DC, spell attack bonus, and spellcasting ability of the original caster, but is otherwise treated as if you cast the spell.

Can Tentacle of the Deeps be cast on the surface of water?

The Warlock subclass The Fathomless has an ability called Tentacle of the Deeps that reads:

You can magically summon a spectral tentacle that strikes at your foes. As a bonus action, you create a 10-foot-long tentacle at a point you can see within 60 feet of you. The tentacle lasts for 1 minute or until you use this feature to create another tentacle. When you create the tentacle, you can make a melee spell attack against one creature within 10 feet of it. On a hit, the target takes 1d8 cold damage, and its speed is reduced by 10 feet until the start of your next turn. When you reach 10th level in this class, the damage increases to 2d8. As a bonus action on your turn, you can move the tentacle up to 30 feet and repeat the attack. You can summon the tentacle a number of times equal to your proficiency bonus, and you regain all expended uses when you finish a long rest.

Would that be able to stand on the surface of water?