Taking one hand off a weapon does not use up any part of the action economy
There is a list of things you can do with your object interaction on your turn and a number of them involve picking things up, drawing things, or putting things away into specific places. Conspicuously missing from this list is anything about simply dropping an item nor anything ...
It would interrupt the spellcasting.
The PHB (p. 203) and basic rules explain how concentration works:
[...] The following factors can break concentration:
Casting another spell that requires concentration. You lose concentration on a spell if you cast another spell that requires concentration. You can't concentrate on two spells at once.
Beastmaster Rangers impart various penalties upon animals they take as companions, of which the chief ones are, as you mention, the action economy penalty and the limitation on what sort of actions may be taken. These penalties last only while the Beastmaster is not incapacitated or absent; if the companion finds itself in either situation the debuffs ...
You can cast the spell
Xanathar's Guide to Everything (p. 77) offers the following rule regarding simultaneous effects:
If two or more things happen at the same time on a character or monster's turn, the person at the game table – whether player or GM – who controls that creature decides the order in which those things happen.
The wave of lethargy ...
Hammering Horns is its own specific action with its own rules
As you've quoted, the Hammering Horns trait of the minotaur player race is specific in how it works and what it does. It unequivocally states that you start with 'unlocking' the ability by taking the Attack action (my emphasis):
Immediately after you hit a creature with a melee attack as part ...
It's not the best wording, but I believe the shove in Hammering Horns is separate from the Shove detailed elsewhere
Let's look at the Shield Master feat
[...] If you take the Attack action on your turn, you can use a bonus action to try to shove a creature within 5 feet of you with your shield. [...]
Here what it means to "shove" a creature is not ...
Unfortunately, Hammering Horns can't knock the target prone
Firstly let's observe the Minotaur's Hammering Horns trait from the Guildmasters' Guide to Ravnica (p. 19; emphasis mine):
Immediately after you hit a creature with a melee attack as part of the Attack action on your turn, you can use a bonus action to attempt to shove that target with your ...
You can't shove prone with Hammering Horns, according to the developers
Rules designer Jeremy Crawford mentions in this unofficial tweet from November 2016:
The first benefit of the Shield Master feat relies on the shove rule (PH, 195), which lets you knock a creature prone or push it away.
This might lead you to believe that Hammering Horns is similar ...
No, the shove from Hammering Horns can't shove the target prone
Rules do what they say they do. Nothing in the rule says you can knock a target prone, so sadly you can't.
As far as the timing goes, Hammering Horns is much more specific than the Shield Master feat. You must make the shove attempt immediately after hitting a creature, not before. Unlike ...
The "Talons" action is the Talons action, not the Attack action.
However, the owl can take the Attack action and use its talons to make an attack
Note that all capitalization in the preceding sentences is significant.
The Monster Manual (p. 10) is clear that the actions listed in the stat block of a creature are additional to and different from the ...
Yes by taking the Attack Action.
The Attack Action in the PHB (p. 192) states:
With this action, you make one melee or ranged attack.
As discussed in this answer a beast's attacks as listed in their stat block qualify as using natural weapons. If the character has access to a weapon they can take the Attack Action to make an attack with it. The Talons ...
D&D is not a physics simulator.
Momentum isn't something that's considered in D&D 5e rules, for the most part. And when it kind of is it's baked into the specific description of the "ability".
For instance, the jumping rules state:
Long Jump. When you make a long jump, you cover a number of feet up to your Strength score if you move at least 10 ...
It counts as a bonus action spell, and thus you cannot cast another leveled spell on that turn
The language of the feature is fairly clear:
As a bonus action, you cast command...
Since you are casting a spell as a bonus action, you would be unable to cast leveled spells as addressed in this Q&A and in the Basic Rules:
You can't cast another spell ...
You are effectively asking if a spellcast that is granted by a class feature that is not the Spellcasting feature is subject to the "only one non-cantrip spell may be cast per turn rule."
The answer is that it is and therefore you may not.
The rule for casting a bonus action spell states:
A spell cast with a bonus action is especially swift. [...] You ...
No, it can only use the actions in its statblock
The text for the steel defender feature reads:
It can move and use its reaction on its own, but the only action it takes on its turn is the Dodge action, unless you take a bonus action on your turn to command it to take one of the actions in its stat block or the Dash, Disengage, or Help action.
Yes, you can take -5 to hit/+10 damage on the bonus-action attack.
The Great Weapon Master feat (PHB, p. 167) reads:
[...] you can make one melee weapon attack as a bonus action.
Before you make a melee attack with a heavy weapon that you are proficient with, [...]
So whenever you make a melee attack (with a heavy weapon that you are proficient ...