Best solo synergies for Swarmkeeper Crusher

[Alea]

I like the idea of a build with three fixed facets:


Swarmkeeper Ranger’s Gathered Swarm, especially the ability to make the target of an attack save against being moved 15 feet
The Crusher feat, which moves the target of a bludgeoning-damage attack 5 feet with no save
The magic stone cantrip, which allows me to deal Wisdom-based ranged bludgeoning damage


All of these options can be achieved as a 3rd-level Ranger by a variant human or a custom lineage. Both the Gathered Swarm ability and the Crusher forced movement ability can only occur once per turn. I can move a target 20 feet if they fail a save, and 5 feet at a minimum. Plus each of these also comes with other benefits (Gathered Swarm can move me or just deal extra damage, Crusher can give everyone advantage against my target if I crit, and of course Ranger is more than just the subclass)—I don’t think those are as interesting, but they’re certainly there. So I’m happy with this base.

The question is: where do I go from there? My big concern is that moving enemies around doesn’t tend to matter much very often. Sometimes there might be a convenient pit or something. Maybe my allies are creating hazardous zones. So if I have 17 levels and however many feats, and can expect some modicum of magic items, how can I best weaponize this forced movement from within my own build?

Actions, I suspect, are the big problem—magic stone costs a bonus action often, and actually attacking requires an action every time. Most things that are going to create convenient hazards are going to take actions too—and even if they last for a while, a lost turn like that is painful. Better answers would be things that can be done more quickly, or that last long enough and are portable enough that I don’t have to spend the action on them in-combat. But there may not be good answers like that.

[RedDew123]

I personally like Spike Growth. You can continue taking Ranger levels to level 5. Spike Growth deals 2d4 for every 5 feet a creature moves within the area. It is also difficult terrain. This does not affect how easily you can push them, but does affect how easily they can escape. There are a few neat ways to get Spike Growth out early. You can:


Take 2 levels in Fighter for action surge. (Maybe start your level path as 1 fighter for proficiencies.)
Take the new Metamagic Adept (Quickened, Subtle) Feat. Which allows you to cast it as a Bonus Action.
Spike Growth has a duration of 10 minutes. And it is camouflaged to look natural. You can cast it outside of combat and lure enemies into it.



Level 5 Ranger also gives you extra attack for some free damage. Since Magic Stone is a cantrip with a duration, your DM might allow you to have it up with some amount of time remaining at the start of combat.
Spike Growth is great for both damage and control. Just be aware that this damage affects everyone who steps into the AoE!

[follacchioso]

This is an interesting idea, but I think it doesn't work.

As a ranged character, you will be fighting less effectively than a ranger with a longbow, due to smaller damage due, smaller range, and dependency on bonus action to renew your pebbles.

As a melee fighter, you are better off with a club and a sling for ranged attacks.
Note that magic stone is a VS spell, meaning you need either a free hand to cast it, or warcaster. This means you can't use a shield with it.

An alternative is to get one or two level in genie warlock (dao), to add your bludgeoning damage every turn.

Moving opponents is a very powerful way to counter melee enemies. A good race could be orc, which allows you to dash closer to the enemy, move it further away, retreat out of reach, and repeat.

[nickl_2000]

It's all about setting up your own traps. Caltops, the Web spell (which you get as a Swarmkeeper), Ball Bearings, Spike Growth.

If you want to lean into that more, multiclass into Druid to pick up many, many other area damage spells.

[Damon_Tor]

Forced movement is best when combined with effects that slow or immobilize the target: so you put them where you want them and keep them there. Ensnaring Strike is a fairly economical way for a ranger to do this.

If you weren't locked into a sling for ranged attacks I would note the synergy with Arcane Archer's grasping arrow. Use the forced movement from swarmkeeper to trigger the bonus damage from grasping arrow, while retaining the push/lockdown synergy.

[quindraco]

I like the idea of a build with three fixed facets:


Swarmkeeper Ranger’s Gathered Swarm, especially the ability to make the target of an attack save against being moved 15 feet
The Crusher feat, which moves the target of a bludgeoning-damage attack 5 feet with no save
The magic stone cantrip, which allows me to deal Wisdom-based ranged bludgeoning damage


All of these options can be achieved as a 3rd-level Ranger by a variant human or a custom lineage. Both the Gathered Swarm ability and the Crusher forced movement ability can only occur once per turn. I can move a target 20 feet if they fail a save, and 5 feet at a minimum. Plus each of these also comes with other benefits (Gathered Swarm can move me or just deal extra damage, Crusher can give everyone advantage against my target if I crit, and of course Ranger is more than just the subclass)—I don’t think those are as interesting, but they’re certainly there. So I’m happy with this base.

The question is: where do I go from there? My big concern is that moving enemies around doesn’t tend to matter much very often. Sometimes there might be a convenient pit or something. Maybe my allies are creating hazardous zones. So if I have 17 levels and however many feats, and can expect some modicum of magic items, how can I best weaponize this forced movement from within my own build?

Actions, I suspect, are the big problem—magic stone costs a bonus action often, and actually attacking requires an action every time. Most things that are going to create convenient hazards are going to take actions too—and even if they last for a while, a lost turn like that is painful. Better answers would be things that can be done more quickly, or that last long enough and are portable enough that I don’t have to spend the action on them in-combat. But there may not be good answers like that.

If you're willing to commit to the same bag of tricks without being attached to Ranger, this gets much easier:
Race: TCL, CHA 17 CON 15 DEX 15 8 everywhere else.
--Feat: Telekinetic (Charisma) or Crusher
L1: Warlock (Genie) (Dao)
L2: Agonizing Blast, Repelling Blast
L3: Pact of the Tome (for more cantrips; you could take the underpowered Pact of the Talisman because it has a knockback invocation, but I really don't recommend it)
L4: The other of Telekinetic or Crusher
L5: Grasp of Hadar
L7: Lance of Lethargy

As you pointed out, action economy is necessary if you want to do this solo, since the best uses of forced movement involve hazards you need to spend your action economy to drop. A 2-dip into Fighter for Action Surge or a 3-dip into Sorcerer for Quickened (despite it colliding with Telekinetic) will take you far.

Here's the net effect at L7, ignoring action economy woes:
1) You have spike growth, create bonfire, cloud of daggers, sickening radiance, etc available to you as spells. Drop one of them on or near your target, depending on its specific wording (but usually on is best).
2) Shoot your target twice, at +7 to hit and +4 damage. Both beams can inflict up to 10 feet of knockback. Up to one beam can inflict up to 10 feet of pull, up to one beam can reduce the target's speed by 10 feet, and up to one beam can move the target up to 5 feet in any direction, provided it's small enough; that same beam is at another +3 damage (total +7). None of these effects allow a save. Your primary goal is adding hazard damage to your damage, which is easiest with spike growth, as it has no 1/turn limit.
3) Bonus action make the target pass a DC 15 Strength save or you can push it or pull it 5 feet. This can happen between your actions, if you're using Action Surge to solve problems - you can drop spike growth, then telekinetic, then cast eldritch blast.

If you assume the target is squarely within spike growth, this is your total damage:
1) First hit: trigger all optional effects. Push the target 10 feet with Repelling, lift it 5 feet into the air with Crusher, then pull it 10 feet with Grasp of Hadard. Total damage: 1d10+4+3+(2d4*5=10d4) = 37.5
2) If the second blast hits, all it has is repel. 1d10+4+2d4*2 = 19.5
3) DC 15 save or take 5 more damage. Note that this is worse than Maddening Hex, but we were trying to commit to forced movement as a meme.

There are better ways to spend your bonus action when you have precious resources available, like a Quickened spell (for more repelling blast shenanigans), which costs sorcery points, or Maddening Hex, provided the target is already Hexed. If you're willing to be a team player, Hex should be one of your go-tos, because you can target Strength with it and make the target easier to shove and grapple, provided your party has a shover in it. You can be your own shover with some class level juggling - swap DEX 15 for STR 15 and ensure your first level is in fighter or paladin so you can be proficient in heavy armor. This also opens up other feats for forced movement, like Skill Expert (Athletics), which has excellent synergy with Hex, and Shield Master, but this requires you to wade into melee, which is not where you want to be.