No, a Warlock with the Pact of the Chain feature does not receive Magic Resistance if they choose a Quasit, Imp, or Pseudodragon. In the first place, a variant rule is only in play if the DM chooses. However, even if the DM decides that pseudodragon familiars (for example) are a thing, it still doesn't benefit the Warlock.
Some pseudodragons are willing to serve spellcasters as a familiar. Such pseudodragons have the following trait.
So "some pseudodragons" will be familiars who share Magic Resistance with their masters. The Warlock, however, gets their familiar from the find familiar spell, which says:
You gain the service of a familiar, a spirit that takes an animal form that you choose: [...]
The Pact of the Chain says that:
When you cast the spell, you can choose one of the normal forms for your familiar or one of the following special forms: imp, pseudodragon, quasit, or sprite.
In other words, the Warlock's familiar isn't any sort of pseudodragon, let alone one with the variant. It's a spirit that takes the form of a pseudodragon (and can take a different form anytime the Warlock chooses). The spell does say that:
[...] the familiar gains the statistics of the chosen form [...]
However, the statistics of a creature are defined on pages 6-11 of the Monster Manual. The short definition is that, if you look at a creature's entry, it's everything in the yellow box. This doesn't include variant traits like the Familiar trait - those are in green boxes off to the side.
All of that aside, a generous DM could, of course, allow a Pact of the Chain familiar to provide its master with Magic Resistance. It must be pointed out, though, that this is making the Pact of the Chain vastly more powerful than it normally is, so DMs thinking about it should consider carefully.
An even more generous DM could allow any player to gain the service of a creature with the familiar variant. This, too, should be considered carefully - it's effectively giving the player a more powerful version of the Pact of the Chain feature for free.
Health Status
Generally I follow a health status report system (when asked how each creature looks) like this:
- 100% - Uninjured or in perfect condition
- >75% - Minor injuries, doesn't show any signs of slowing, just a few minor inconveniencing injuries
- >50% - Injured, visibly wounded with some nondebilitating injuries, but still fighting strong
- <50% - Bloodied or Heavily Injured, starting to look more ragged or visibly slowing down
- <25% - Severely injured, looking in bad condition, unable to fight or survive much longer
- <5-10% - Critically injured, barely hanging on, one more solid blow may take them down (if true)
You can add in some injury flavour according to what you've already described on that target, so no giant cuts if everyone is hitting it with hammers.
As the target takes injuries, I describe them according to where on the chart they currently are, and where the damage would make them fall to.
Transition examples
- A creature at Uninjured that drops down to Bloodied or lower, or from Injured to Critically injured (a 4 tier drop) has just taken a devastating strike, a solid stab or slash to the gut or chest, or a sickening crack as the maul comes down. I often use this level of drama for critical hits as well.
- Uninjured to Minor injuries (or similar 1 tier drop) was only a glancing blow, or the creature managed to evade or absorb the brunt of the attack. As they drop into lower tiers, I describe the hit that connects as more damaging (eg, slashes instead of minor cuts), and the creature as being able to absorb or evade less.
- A drop of around two or three tiers or an injury while at a lower than 50% tier is a solid hit, a sizable cut across the arm or leg, a powerful thud as a maul connects with a shoulder or chest, or an arrow puncturing and sticking solidly into the creature.
Note that you'll have to adjust your descriptions to make sense for your target. A slime may begin looking like it's form is struggling to hold together, or large pieces have been cut or smashed off of it, for example.
When to Describe
It's perfectly normal for players to ask for updates, as the players don't have the health numbers in front of them, and is not necessarily reflective of poor narration. It's easy to forget which bad guy was injured, and how badly they were hurt in between turns.
As for how often to describe, whenever the players ask for a battlefield summary (to try to decide who to prioritize) you should give a health status on each creature. You're their eyes into the world, so describe what they see whenever they ask. Additionally you should also describe the status whenever they drop a tier or more, so it clearly indicates the full effect of the blow. Use the descriptions of their attacks to help narrate this tier transition.
Your sword finds its way around the Hobgoblins shield, cutting a large gash up his chest, he clutches it for a moment and is looking quite ragged and breathing heavily.
You don't need to know the damage roll or the Hobgoblins hit points to know that attack did a number on him, and that he's now quite injured, to the point a follow up may kill him.
Best Answer
Creature is basically every living, breathing (or undead or constructs) thing big enough to be considered at least CR0 (give or take).
It's important to note that "creature" does not get a precise definition in the rules. However, we can infer from BD&D p4 that it includes both the PCs and the creatures they encounter.
Thus we can say with some certainty (and examining how the word is used throughout the text) that creature is the broadest definition of living thing. If a spell, effect or condition affects "creatures" then it affects everything it targets.
Character is ambiguous by default and is used by itself to refer to both non-player characters and player characters depending on context. When it is ambiguous to which it refers, it should be clarified to be player or non-player.
Player character refers to characters controlled by players and is a subset of both humanoid and creature.
Non-player character (NPC) is usually a humanoid, but can sometimes refer to all DM controlled creatures. It is exclusive of PC and is a subset of creature.
Monster is exclusive of NPC and PC usually, but is still a subset of creature.
Humanoid is a subset of creature, and is generally inclusive of PCs and NPCs (though not always). It refers to anything even vaguely humanoid. Relevant quote:
So in summary, when it says "creature", it means everyone, if it says "humanoid" it generally means one of those races. If it says "player" or "character" or "player character" it means a player controlled character. If it says "non player character" it means a DM controlled one (could be monster or NPC though).