So I homeruled an enchanted set of lockpicks with Knock (the level 2 rogue who bought them calls them his Knockpicks). He can use them 1/day and they recharge at midnight. What the NPC who sold them to him did NOT tell him was that they're also cursed. While attempting to pick a lock with these picks in his possession, rolling a 1 or 2 triggers the Knock spell, even if it's been used willingly. For a stealth-based class, I thought it was a sadistically hilarious way to give him what he wanted (better access to loot) while setting the party up for situations where they're sweating bullets over the results. Great roleplaying tool, and if the curse proves too much for his tastes he can pay to have the curse lifted for a +1 set of Lockpicks.

Why is it called Knock, and not Unlock?

Because part of its balance includes that it creates a really loud sound

Could a dispel magic has similar effects to knock? 

Fangmay, dispel magic could dispel certain magical means of preventing access to things, but it can't dispel mundane means, like a simple lock.

I'd assume because of the extremely loud noise it produces to open the door, as if your knocking to be let in.

This is a spell that it would be useful to get on a cleric domain.

can you mitigate the knock with a silence spell application?

I am a little surprised this spell is not on the Artificer spell list.

Because of the verbal component in silence it will be unable to be performed at all

knock has a 60ft range, caster can be outside the silence area to cast knock, the "knock" sound emanates from the target object which can be under a silence aoe. it is an expensive use of spells to do so, and not all area's may have the space for the silence/knock to be used like this, so imo yes they can be used together however they are very situational in usability.

Will Knock work on a door that's been sealed by Stoneshape?

Depends on what you mean by sealed. If the door's opening mechanism is destroyed and a single stone, no, I don't think so. By my understanding, it could open a door latch created by Stone Shape, though.

I wonder if the wording "a target that is stuck" is also intended to extend to knots? But maybe only with knots that were tied with two ends, like a classic ribbon or an eighth knot? Idk, as a DM I would allow knots, since imo a knot counts as a  mechanism by which a passage can be barred, locked or made stuck.

Quote from Psytama >>

Because of the verbal component in silence it will be unable to be performed at all

 Unless cast with subtle spell metamagic which removes verbal requirements.

So this plan might work, Or you could take advantage of the 60 ft. range of the spell.

As it states that a target under the effect of Arcane Lock has the effect suppressed for 10 minutes, will a second casting of Knock open a target? 

I think knock should have a cantrip level version for normal locks that works just like thieves tools. You still have to succeed on the attempt, but doesn't require an actual tool.

As a second level spell, knock a lot of opportunity cost to prepare over other spell options. Its real use comes in as a means of suppressing arcane locks, but its use to automatically unlock a lock, with a loud knock heard up to 300 feet away is not really second-level caliber. (If it did so silently, it might be worth a second level spell slot.)

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Quote from MagicalMedic >>

So I homeruled an enchanted set of lockpicks with Knock (the level 2 rogue who bought them calls them his Knockpicks). He can use them 1/day and they recharge at midnight. What the NPC who sold them to him did NOT tell him was that they're also cursed. While attempting to pick a lock with these picks in his possession, rolling a 1 or 2 triggers the Knock spell, even if it's been used willingly. For a stealth-based class, I thought it was a sadistically hilarious way to give him what he wanted (better access to loot) while setting the party up for situations where they're sweating bullets over the results. Great roleplaying tool, and if the curse proves too much for his tastes he can pay to have the curse lifted for a +1 set of Lockpicks.

 Knockpicks...I snorted. 

Does Knock also open the object or just unlock it.