So, by this point ive figured out that i need to name the feature "spellcasting" or "pact magic" in order to get it to work, but im absolutely flabbergasted as to how to do anything else.

How do i set weather i want it to be a full, half or quarter caster? how do i set how many spells i want it to know? how do i disable cantrips? how in the sam hell does it know that i wanted the ranger spell list?

Im so confused, the blank pact magic feature seems to have taken info from an entirely separate feature in the subclass and used it to try and auto generate the pact magic feature. Its set the default spell list to ranger on its own (what i wanted, but i would still like to know why). Its saying i can pick cantrips, but doesnt give me the option to do so in the subclass

Basically my question is, how do i control the parameters of a spellcasting/pact magic feature? do i just type out the description and hope some AI reads it correctly?

Update; ive been playing with it a bit more, and it seems that every class (including barbarian and monk) has a preset number of cantrips and spells that they learn, and they are locked to quarter caster progression. 

also of note, even though the subclass builder presents an option to say spells can be prepared (cleric, druid, pally), this option does not actually work. it just sets every spell on the spell list to 'learned' and breaks the character if i try to 'unlearn' a spell.

I've been trying to get Pact Magic built into a class other than Warlock (Rogue, in this case) for a couple of months now.  There doesn't seem to be any option to add warlock Pact progression to any class other than warlock, and regular casting is limited to bog-standard quarter-casting, yeah.  It's super frustrating.

Instead of trying to make a base Ranger or base Rogue with Warlock features, have you tried making a base Warlock with Rogue or Ranger features?

Heh.  Sure, but it wouldn't be what I was trying to do.  Any jackwaffle can slap extra thief-y proficiencies on a warlock, but it wouldn't be the Beguiler I was trying to build, it would be a warlock with thieves' tools.

It'd be great if DDB allowed a homebrew editor to tailor her class's spellcasting progression, because a lot of folks I know would like to make warlock-inspired half-casters.  I know it's possible, because they did exactly what I was trying to do with the Order of the Profane Soul for Blood Hunters.  That is the exact half-Pact progression I was looking to bake into the Beguiler, so I know it exists and can be done in the builder, but nobody knows how, and no amount of studying my copy of the Profane Soul has shown me how.

Im trying to make a firearms rogue subclass, with a profane soul style spellcasting feature. Here it is)

(Ive expanded slightly on mr mercers firearms system, so thats what clockwork pistols, lever rifles, and range finders are from)

Dark Marksmen

Bonus Proficiencies

When you choose this archetype at 3rd level, you gain proficiency with Palm Pistols, Pistols, Muskets, Clockwork Pistols, Lever Rifles, and Range Finders.

Black Magic

When you reach 3rd level, you can augment your combat techniques with the ability to cast spells. See chapter 10 of the Player's Handbook for the general rules of spellcasting and chapter 11 in the Player's Handbook for the Ranger spell list.

Spell Slots. The Dark Marksmen Black Magic table shows how many spell slots you have. The table also shows what the level of those slots is; all of your spell slots are the same level.

To cast one of your ranger spells of 1st level or higher, you must expend a spell slot. You regain all expended spell slots when you finish a short or long rest.

For example, when you are 8th level, you have two 2nd-level spell slots. To cast the 1st-level spell charm person, you must spend one of those slots, and you cast it as a 2nd-level spell.

Spells Known of 1st Level and Higher. You know three 1st-level spells of your choice from the ranger spell list, two of which you must choose from the divination and transmutation spells on the ranger spell list.

The Spells Known column of the Dark Marksmen Black Magic table shows when you learn more ranger spells of 1st level or higher. Each of these spells must be a divination or transmutation spell of your choice, and must be of a level for which you have spell slots. For instance, when you reach 7th level in this class, you can learn one new spell of 1st or 2nd level.

The spells you learn at 5th, 8th, 11th, 14th, 17th, and 20th level can come from any school of magic.

Whenever you gain a level in this class, you can replace one of the ranger spells you know with another spell of your choice from the ranger spell list. The new spell must be of a level for which you have spell slots, and it must be a divination or transmutation spell, unless you're replacing the spell you gained at 3rd, 5th, 8th, 11th, 14th, 17th, and 20th level from any school of magic.

Spellcasting Ability. Wisdom is your spellcasting ability for your ranger spells, so you use your Wisdom whenever a spell refers to your spellcasting ability. In addition, you use your Wisdom modifier when setting the saving throw DC for a ranger spell you cast and when making an attack roll with one.

Spell save DC = 8 + your proficiency bonus + your Wisdom modifier

Spell attack modifier = your proficiency bonus + your Wisdom modifier

Ricochet

At 9th level, you can cause your firearm attacks to rebound off of solid surfaces, such as stone or steel, in order to strike unsuspecting enemies.

If a target that you are aware of is within 10 feet of a solid surface that you can see, you can attempt to hit the target with a ranged weapon attack made with a firearm.

At 17th level, the bullet can ricochet twice before hiting the target, so long as both of the solid surfaces and the target are no more than 30 feet apart.

Hunkered Shot

At 13th level, while you are prone, you can choose to gain the following benefits:

• You have advantage on any ranged weapon attack roll you make with a firearm, and you can use your Sneak Attack against a creature so long as you don’t have disadvantage on the attack roll.
• Any hit you score with a firearm against a creature that hasn’t taken a turn in the combat yet is a critical hit.

Once you make use of either of these two benefits, until the beginning of your next turn your movement speeds become 0, and you cannot benefit from any speed increases.

Standoff

At 17th level, whenever you take the dodge action on your turn, and have no weapons drawn, you can prepare yourself to strike at the perfect moment.

Until the beggining of your next turn, if you see a creature that is within range of one of your loaded firearms attempt to: move, cast a spell, or make a weapon attack roll; you can use a reaction to draw a loaded firearm and make an attack of oppertunity against them. On a hit, the shot deals its normal damage, and the target must make a Constitution saving throw against your marksmen spell save DC. On a failed save, the target is stunned until the start of its next turn, and its spell or attack fails (if any).

You can use this feature a number of times equal to your Wisdom modifier, regaining all uses after you finish a long rest.