What would be the most optimal way for a Pact of the Chain warlock to make use of a Sprite familiar?

Question

I am playing an Archfey Warlock with the "Pact of the Chain" Pact Boon. For thematic reasons, I have chosen for my familiar to take the form of a sprite with the "fey" creature type.

The restriction I place on this question is that the above facts must remain true, these are fixed aspects that I do not want to change; hence any answer that states that the familiar should take another form, like an imp, are not valid answers to this question, regardless of how much more optimal that might be. In other words, this is not "how to optimise a Pact of the Chain warlock", but "how to optimise the use of the sprite as a Pact of the Chain warlock's familiar".

Further restrictions are that I do not plan on multiclassing, so answers that require multiclassing are also not valid answers, and that I am limiting the range of levels in play to between 3 and 7, so answers that require me to be a higher level warlock are also not valid (although if an answer includes a "here's what you can do at high levels too" section as an added extra, I won't complain).

Given these restrictions, I want to get the best use out of my sprite familiar. Because of it's tiny HP pool, so far I've just had it remain invisible and hide out of sight so that it doesn't get shot and killed, since I'm still currently only level 3 and don't really want to waste the resources resummoning it (later in the game, I assume this won't be as much of a problem, but let's assume that the familiar's survivability is a concern of mine nonetheless, but not actually a hard restriction).

What are the best tactics to employ to make the sprite familiar as useful in combat as possible during late tier 1/early tier 2 play? I'm happy for people to suggest spells and invocations that the warlock themselves should pick in order to support the tactics that would enhance the sprite's usefulness, but I don't want this to turn into a question about optimising the warlock themselves; the focus should be on the sprite (in other words, assume the warlock is already optimised well enough for the purposes of this question).

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Related Q&A: What can a familiar actually do? (except this question is about familiars generally, and the answers do not take into consideration the traits specific–if not unique–to a sprite, such as invisibility or potentially being able to poison an enemy or make it fall unconscious with the sprite's shortbow attack)

Related Meta Q&A: Would this question about when it's better for a Pact of the Chain warlock to have their familiar attack be an on-topic bounded list question? (although no-one seemed to have an opinion either way, so I've gone ahead and asked it anyway; however, this meta Q&A can still be used as a platform to discuss the on-topic-ness of the question, should that become necessary)

Answer 1

There are a number of ways to make use of a sprite familiar. Here are some of them:

• Get them a healer's kit and potions to help take care of downed party members without costing a PC an action
• Give them caltrops to help control the terrain
• Have them "Help" every round. This is commonly used by regular familiars but Warlock familiars are especially good at it. Remember that if the enemy cannot see it the sprite does not provoke opportunity attacks. Since the sprite has 40 speed it should generally be able to fly in, distract the enemy, and fly out without being in danger.
• Have the sprite "Help" on intelligence checks or rather help the sprite. This a the big advantage of sprites over other familiars in that they have 14 INT. This means, depending on your build, they likely have higher intelligence than you and have a better bonus in knowledge areas where you lack proficiency. You can help the sprite by sharing what you know to give it advantage on the check. In general have the sprite try to help on every skill check you can justify. This is easy in cases of keeping watch or investigating but you can also possibly use your little friend on other types of checks. Sprites are generally good so have them vouch for your honesty if you are trying to lie. See if they can lightly touch someone so you can learn their emotional state via Heartsight and so be able to persuade them more easily. The possibilities depend on your imagination and on your DM's judgement.
• Send them to spy on the Bad Guy. Considering their stealth and invisibility they are impossible for anyone with less than 14 passive perception to detect so long as they keep hiding. They are smart enough to take complex directions so you can have them go spy for three days and then dismiss them and resummon them to hear what they discovered.
• If you have a magic item that doesn't make an attack roll consider giving it to the sprite. I think a Bag of Tricks would be exceptionally appropriate but an item like the Gem of Brightness would also significantly boost your tiny friend.
• They have a ranged attack so it might be situationally useful. Unless you are fighting other familiars the damage is negligible and certainly not worth your action or exposing your familiar. I would suggest only using it in specific tactical scenarios. When you have a foe with weak constitution the poisoned debuff can be debilitating so you might choose to start a combat by having your sprite poison someone. This will become less useful at higher levels because the save DC remains quite low. Alternatively you can use it as a hail mary to disable a lone guard out of combat. There is a slim chance of putting a target with less than +5 to con saves to sleep. You can also try to use the sprite to set up an ambush. Have the rest of the party hiding behind full cover and have the sprite invisibly wait until the foe appears before firing an arrow. If you are lucky the villain is poisoned or asleep. At the very least you have a decent chance of surprising them at which point the rest of the party comes out and starts wailing on them.

It it worth noting that, unless your DM has something against familiars, an enemy is unlikely to target the invisible creature (disadvantage) that helps the sword swinger over the sword swinger. The main dangers to your companion are AOEs. Keep an eye out for potential threats like this and try to keep the sprite away from the center of the party and preferably behind cover. If the sprite does die you will still function as a warlock. Just try to pick up 10 gold worth of incense and re-summon them.