I managed to get Wicce Deneb in a few hours (including the goth needed to buy the orbs) and wanted to share my method because I think it is pretty efficient. It requires WORLD Tarot and abusing CHARIOT.
-------GETTING CRYSTAL PUMPKINS-------
1) Use WORLD to go Coda anchor point:
Head to the first floor of the Palace of the Dead. Make at least three characters archers, I used Canapus, Hobyrim, and Arycelle. It helps if they can one shot (My level 25 Canapus Archer with 8(+2) Bow skill had no problem but Arycelle with 5(+2) could almost one shot) because it will obviously be faster. Give them a Seige Bow +1, Brigandine +1, Ring of Deftness +1, and Nomad Bracers +1 (their RT should still be lower than all the enemies). For skills give them Bows, Aurology, and Deamonology. Start a battle in 1F of PofD. The two enemies that you are looking for are a Farie (17 elev) and an Umbra (elev 11) Familiar. I circled them in this SS:
If neither is there, retreat. If either one is there kill them. Archers can hit either of them with Seige Bows. Since I can only one shot with Canapus, I use the first turn to damage the Umbra:
Then send Canapus to one shot the Farie:
Then have Arycelle finish off the Umbra:
If a card ever drops:
Hit O to deselct the Character then L to bring up the CHARIOT Tarot:
Then hit X to redo the turn (this won't count towards your CHARIOT count unless you do it on the first turn), move over to the next spot and try again (repeat until you find a spot that gives a bag). This can be used to max your chances at farming/taming anything, btw:
Retreat from the battle to collect the bags. If you're lucky you'll get a pumkpin, and you'll get Baldur bows, daggers, armor, bucklers, and wizard hats that you can sell for Goth when you're done. If you're really lucky you'll get two pumpkins (one from each Familiar):
Make sure to save every now and again. Repeat until you have 30. It should take about 2 hours total (~15 Pumpkins per hour). You'll also be accumulating gear to sell for Goth that can be used to buy the dragon orbs. I got something like 40 bucklers, 20 daggers, bows, armors, and wizard hats. I sold it all and got over 250.000 Goth, enough to buy all the orbs (after reselling most of them) and not counting money from auctioning the dragons (I didn't track that).
-------GETTING DRAGONS-------
To get common dragons, head to Phorampa Wildwood (during any point) and open the second map on the North Branch, "Field of Fallen Shadow":
You can abuse the CHARIOT tarot the same way you can to farm bags in order to max your chances. Just remember that if you move, use an action, and use a skill in the same turn and use the CHARIOT it will count towards a use, if you only use two of the three (e.g. Move+Tame, Attack+Tame, or Move+Attack) you can use CHARIOT before ending the turn without creating a new branch.
To get the more exotic dragons and the Hydras use the WORLD Tarot to go the Anchor Point after Barnicia Castle:
Head towards the (now current) story battle at Madura Drift. On the way there you'll go through Phidoch castle and get 5 Pricess or Lord Marks that you can sell for 2500 goth or keep:
The map has a hydra and the dragons you can't get from the wildwood map (e.g. Arc. Dark). The hydra will be in the lower left corner:
There will also be either an Onyx (dark) or a Crystal (light) dragon on the map, just ignore them since you can't Tame them. After you clear the map (and tame your hydra), use the world to go back to the anchor point and repeat two more times to get the other two hydras. You can auction the dragons anywhere just make sure to buy the orbs from Deneb. You only really need one of each type (except the hydras) and use a mark to change extras over to whatever else you need.
That should get you everything you need to get your dragon types, your pumpkins, and all the goth you need to buy everything. Use the WORLD Tarot to go to the Coda again (to assure that Vasque is open), then buy the orbs from her. I needed to sell back some of the orbs I bought to get enough goth to buy the last 5. Also make sure to sell her the Pumpkins before buying the last orb. After that she'll start her quest. Head to Vasque and kill her Punkin doppledanger:
That's it. It should only take a few hours. I also noticed that during the CODA the day doesn't change when you move about, making it easier to find her shop when you need to buy the orbs. Here is a list of her shop locations on the different days:
Day - Location
1 - Port Omish
2 - Grimsby
3 - Heim
4 - Oeram
5 - Barnicia
6 - Golyat
7 - Almorica
8 - Rhime
9 - Krysaro
10 - Phidoch
11 - Balmamusa
12 - Coitanae
13 - Asyton
14 - Brigantys
15 - Omish
16 - Grimsby
17 - Heim
18 - Oeram
19 - Barnicia
20 - Golyat
21 - Almorica
22 - Rhime
23 - Krysaro
24 - Phidoch
25 - Balmamusa