Just for additional clarity, the normal forms are listed in the spell description of Find Familiar.
You can use the Game Rules -> Monsters page on D&D Beyond to find more, just filtering to Beast and CR 0. This link has the filters applied already. There is unfortunately not much on there that would serve well as a pack animal. Maybe a deer.
In practice, if you have Pact of the Chain, there's little reason not to choose one of the special options it grants you, as they all have interesting features and combat capabilities that the normal options don't.
So it appears that there is a goat or sheep or a skeleton that can probably be used as a pack animal.
Is there any issue with using them like a pack animal assuming the aren't scouting or something else? As for combat capabilities, the need for them to take my characters attack action has left me thinking it is not worth using them for direct combat.
As for combat capabilities, the need for them to take my characters attack action has left me thinking it is not worth using them for direct combat.
Most of the time, probably not, though some of the special forms have attacks with rider effects that may be useful at times (e.g. the Quasit's ability to apply the Poisoned condition with its attack, or the Sprite's ability to apply Charmed). Some of them also have non-attack options that they can use on their own turn; in particular, the Pseudodragon has a Sting ability that can knock someone Unconscious.
Also, note that at level 5 you can take the Eldritch Invocation "Investment of the Chain Master", which lets you use your bonus action to have your familiar attack.
There are also CR 0 beasts that are special case creatures and may technically fit the CR 0 Beast restriction but aren't intended to be allowed, such as a Giant Fly (a transformed magic item) or Haungharassk and Onyx (unique adventure NPCs).
Also, note that at level 5 you can take the Eldritch Invocation "Investment of the Chain Master", which lets you use your bonus action to have your familiar attack.
Agreed, assuming you are not doing the invocation of two minds which needs a BA to continue.
There are also CR 0 beasts that are special case creatures and may technically fit the CR 0 Beast restriction but aren't intended to be allowed, such as a Giant Fly (a transformed magic item) [...]
If I have a Warlock with Pact of the chain, I can choose one of the normal forms, but what is that? Is it anything with a CR 0 or less?
Can I choose a pack animal or a Mastiff? If so can I use my familiar to carry my gear like a pack animal?
Can it be a blink dog or even a rust monster or is that a special form?
The animal form you choose when you cast Find Familiar are Bat, Cat, Frog, Hawk, Lizard, Octopus, Owl, Rat, Raven, Spider, Weasel, or another Beast that has a Challenge Rating of 0.
Mastiff No because it's not a Beast with CR 0.
Blink Dog No because it's not a Beast but a Fey.
Rust Monster No No because it's not a Beast but a Monstrosity.
Just for additional clarity, the normal forms are listed in the spell description of Find Familiar.
You can use the Game Rules -> Monsters page on D&D Beyond to find more, just filtering to Beast and CR 0. This link has the filters applied already. There is unfortunately not much on there that would serve well as a pack animal. Maybe a deer.
In practice, if you have Pact of the Chain, there's little reason not to choose one of the special options it grants you, as they all have interesting features and combat capabilities that the normal options don't.
pronouns: he/she/they
So it appears that there is a goat or sheep or a skeleton that can probably be used as a pack animal.
Is there any issue with using them like a pack animal assuming the aren't scouting or something else? As for combat capabilities, the need for them to take my characters attack action has left me thinking it is not worth using them for direct combat.
I wouldn't think so.
Most of the time, probably not, though some of the special forms have attacks with rider effects that may be useful at times (e.g. the Quasit's ability to apply the Poisoned condition with its attack, or the Sprite's ability to apply Charmed). Some of them also have non-attack options that they can use on their own turn; in particular, the Pseudodragon has a Sting ability that can knock someone Unconscious.
Also, note that at level 5 you can take the Eldritch Invocation "Investment of the Chain Master", which lets you use your bonus action to have your familiar attack.
pronouns: he/she/they
There are also CR 0 beasts that are special case creatures and may technically fit the CR 0 Beast restriction but aren't intended to be allowed, such as a Giant Fly (a transformed magic item) or Haungharassk and Onyx (unique adventure NPCs).
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How to add Tooltips.
My houserulings.
Agreed, assuming you are not doing the invocation of two minds which needs a BA to continue.
I agree with you, but... Find Familiar: Giant Fly :)