One of my players rolled a natural 20 for Animal Handling on a grick which had previously been trained by goblins. What happens to the grick now? Can he tame it or should it just now be calmed?
Hold the phone...
The 20 is a failure. Gricks are not “Animals.”
A grick is of the type monstrosity and thus is not an animal. Animals have the type beast.
Monstrosities are monsters in the strictest sense — frightening creatures that are not ordinary, not truly natural
MM, p. 7
Beasts include all varieties of ordinary animals.
MM, p. 6
(And those are the hazards of arguing with your DM.)
Connecting the Dots
The game terms are well-defined. Just to connect the dots, here’s a little formal proof:
- The Animal Handling skill works specifically on animals
- “All varieties of ordinary animals” are beasts
- Monstrosities are not beasts
- Monstrosities are therefore not animals (in game terms)
- We can conclude Animal Handling does not work on monstrosities
The only point to argue, in my opinion, is how much of a loophole the word “ordinary” creates. I would argue not much, as the phrase “all varieties” is expansive.
Taming does not equal Domestication
Some have argued that a “tamed monstrosity” is equivalent to a “domesticated beast” (domestic beats being explicitly called out as valid targets for animal handling). But taming and domestication are different things:
Domestication should not be confused with taming. Taming is the conditioned behavioral modification of a wild-born animal when its natural avoidance of humans is reduced and it accepts the presence of humans, but domestication is the permanent genetic modification of a bred lineage that leads to an inherited predisposition toward humans.
Please note, in this Wikipedia article, “animal” is not a game term.
(Also see CGP Grey’s Zebras vs. Horses.)
A goblin might tame a monstrosity; a drow might tame a slave. Taming them doesn’t make either an domesticated animal.
A word on alignment
All the ordinary animals/beasts in the Monster Manual have an alignment of unaligned — “they don’t make moral or ethical choices, but act on instinct.” (MM, p.7) Grick are aligned neutral, not unaligned. Thus, although they have low intelligence, their minds are different than those of animals.
What about monstrosities that are trainable?
Some monstrosities, such as griffons and hippogriffs, can be trained as mounts. That’s because a specific rule says they can be (under the stipulations set out by those rules).
How could the goblins train this untrainable grick in the first place? Well, that is a decision made by the DM in question. In previous editions of D&D, goblins were known for training all sorts of monsters. In any case, it is not really relevant to the rules analysis here.
Skills checks that could never succeed
Why would a DM call for a skill check that could never succeed, such as an Animal Handling roll on something that can’t be swayed by animal handling? That would be done whenever doing otherwise would give away information to the players (via a little inevitable meta-gaming).
For example, if a druid tries to call a cat over to him, the DM may call for an Animal Handling check (of course). If the cat is actually a polymorphed wizard, the skill check could never succeed. If the druid rolls a 20 and still fails, then that is a hint to the players that something may not be as it seems. If they roll poorly, they may think they simply failed. So there is still a point to the roll.
A Note on Monster Types
It’s worthwhile to get familiar with monster types listed in the front of the Monster Manual. These are not fluff descriptions — they impact game mechanics in lots of ways. See my answer here.
A natural 20 means nothing on a skill check. Only attack rolls have special rules for handling natural 20s (or natural 1s), but skills aren't attack rolls and don't have any special rules of their own for rolling a natural 20.
While the DM is free to change the outcome to something more exciting, the rules say it is merely calmed and nothing else. If the player insists that something extra should happen and the DM doesn't agree, the player should be reminded that turnabout is fair play and the next natural 1 on a skill check will bring catastrophic failure (even though it also should not do that).
First, it seems that you are using the optional rule in the DMG that allow critical success or failure on ability (thus skill) checks. This is indeed detailed on page 242 of the DMG.
Furthermore, as the grick is trained / already tamed I could treat it as an animal. Goblins should train any creature that they can encounter in the vicinity.
A crit' may allow the PC to avoid the dangerousness of the grick and if some time is spent with the creature it can be trained a little bit (not to attack allies, to bring back some stuff, to reach objects for his master, etc ...). The more time spent with the creature and with more other Animal Handling successful checks, the more the creature will be friendly and willing to obey orders.
Under the rules of D&D 5e, it is unclear if Gricks are animals.
All ordinary animals are beasts. This adjective -- ordinary -- weakly implies that there are non-ordinary animals that are not beasts. It definitely does not imply all animals are beasts -- that the two words mean the same thing.
Animal handling works on animals. Nothing in the text restricts it to ordinary animals. So there is no rules as written justification to claim that animal handling only works on creatures of the beast subtype. If that was the case, it would have been easy to use the word beast in the skill definition.
And not being able to use animal handling on a griffon that some Elven Riders where using would be a farce.
If the Grick is an animal, and you consider a tamed animal "domesticated", then it is a valid use of the skill. Each step is the DM's call.