The Ideal Dragon Tail Starting Play
Requires Dragon Tail Fymena and 2 other Dragon Tail monsters. This combo plays around Nibiru, the Primal Being because it only summons 3 times minimum. The Hieratic Seal of the Heavenly Spheres can special summon Dragon Tail Mulr from your deck, whose effect allows you to fusion summon a Dragon Tail fusion monster using the monsters from your hand and on your field during the opponent's turn. All the current main deck Dragon Tail monsters can set a Dragon Tail spell or trap from your deck, so any combination of them can start this play.
1. Activate Dragon Tail Fymena's effect to discard her, then fusion summon Dragon Tail Altharion by using the two other Dragon Tail monsters in your hand as material.
2. Activate Altharion's effect to target, then return Fymena and 1 other Dragon Tail monster back to your hand as chain link 1. Activate the effects of the Dragon Tail monsters used as fusion material as chain link 2 and higher. This chain blocking will protect Altharion from Ghost Belle & Haunted Mansion. Set Ketu Dragon Tail and Rahu Dragon Tail from your deck. If you already have them, then you can set from your deck Dragon Tail Horn and/or Dragon Tail Flame instead.
3. Activate Ketu Dragon Tail to search for Dragon Tail Lucias.
4. Normal summon Lucias.
5. Use Lucias' effect to search for another Fymena.
6. Link summon the Spirit with Eyes of Blue by using Lucias as link material.
7. Link summon the Hieratic Seal of the Heavenly Spheres by using Altharion and Lucias as link material. This will remove the Spirit with Eyes of Blue's special summon lock.
7.5. (Optional) Here you can use Altharion's effect to special summon him back from the graveyard, but he won't do much if you go first. If you're going second then, instead of the Heavenly Spheres route, you can link climb with Altharion and Lucias from Aussa the Earth Charmer, Immovable to Selene, Queen of the Master Magicians to Accesscode Talker.
8. Activate Rahu Dragon Tail to fusion summon Dragon Tail Gramel by using 1 Fymena in your hand and another Dragon Tail monster in your deck as material. Ideally, you'd use whatever Dragon Tail monster you didn't already fuse with this turn to activate its graveyard effect in the next step.
9. Activate the graveyard effects of the Dragon Tail monsters you recently fused with to set Dragon Tail spells and/or traps from your deck.
Your current board should have the Hieratic Seal of the Heavenly Spheres, a Dragon Tail Gramel, a set Dragon Tail Horn, and a set Dragon Tail Flame. You should also have a Dragon Tail Fymena and another Dragon Tail monster in your hand, which will allow you to fusion summon on your opponent's turn. If a Dragon Tail Urgula is in your graveyard, then you can activate its graveyard effect to add a Dragon Tail Lucias from your graveyard to your hand for the following turn. The Heavenly Spheres can bounce a card on the field and summon a Dragon Tail Mulr on your opponent's turn.
On the Primite Engine
The Primate engine allows you to summon the Hieratic Seal of the Heavenly Spheres by using only 1 card and allows you to summon to the Red-Eyes Dark Dragoon by providing to access the Dark Magician. The Dark Magician + any dragon effect monster like Primite Dragon Ether Beryl or Dragon Tail Pan can fuse to make the Red-Eyes Dark Dragoon. Primite Lordly Lode can special summon the Dark Magician from your hand, deck, or graveyard, then Imduk the World Chalice Dragon can convert the Dark Magician into a dragon monster. Imduk + Ether Beryl = the Heavenly Spheres. The Heavenly Spheres can special summon Dragon Tail Mulr from the deck, who can fusion summon Dragon Tail Altharion by using itself and another monster in your hand as material. Altharion can then add the Dark Magician from your graveyard to your hand for a future play.