Mythical Spellbook Endymion

Powerful combo deck (recommended for online play (YGOpro, Dueling Nexus), as keeping track of spell counters irl is a pain) that uses several engines from the following archetypes:

Spellbook (drawing engine)

Mythical beasts (summon negate & monster negates)

Endymion (spell & trap negates & synergy w/MBs)

The main deck involves several going first or second options, and can utilize the side deck accordingly after the first match. The "going first" board is usually ending with two or three negates in the form of Odd-eyes Vortex Dragon (summoned using the effect of Odd-eyes Absolute Dragon), Endymion, The Mighty Master of Magic, Mythical Beast Jackal King and Apollousa, Bow Of The Goddess. You can also end with a Secret Village of the Spellcasters up if you draw into it or Terraforming, as well as a Mythical Beast Garuda in hand, which can use three spell counters to negate the special summon of a monster, on SS2.

The following segment shows how to use all of the engines (It's worth knowing that they are in order of importance/the order you will use them in a duel, this is also going first)

First, Mythical beasts. If you opened Mythical Beast Master Cerberus, as well as Mythical Institution, then go ahead and activate Institution. Then activate Cerberus in the pend scale and use it's effect to pop itself (sending it FU to EX deck) to add one Mythical beast to hand. If you opened Jackal King as well, then search Garuda. If not, get the Jackal King. Then use Jackal King in the pend scale, which pops itself to special summon a face up Mythical Beast monster from your EX deck (Cerberus, which can be linked away for gravity controller to free up the EX MZ). At this point, you should have 4 counters on Institution, as it gains 2 spell counters every time a Mythical Beast blows itself up for it's pend scale effect. If you didn't open Spell power mastery (to add servant) or Servant of Endymion, use institution's effect to add Servant to hand. It's imperative that you do not use any Endymion pendulum cards if you wish to use any Mythical beast pendulum effects, as they shut off if they're not the only card in your pend zones. A high Endymion scale (8) works just fine with the Mythical Beast's 4 for summoning 5-7 (which includes Mythical Beast jackal king (lvl 6), and both Endymion TMMOM and Reflection, both 7). At this point, you will want to move onto using your Endymion cards:

The only Endymion card you won't really want to use in the pend scale (unless you're desperate for a high scale or a singular spell counter) is Endymion (TMMOM) himself. His pend scale effect is cool and all, allowing you to use 6 spell counters on your field to special summon itself, and then target and destroy as many cards as you can on the field, up to the amount of cards you control that can hold spell counters (then giving himself the same amount of spell counters as the amount of cards destroyed), but it's a bit of a win more card. His negate is returning a face up card with a spell counter that you control to the hand, to negate the activation and destroy a S/T and then gain the spell counters the bounced monster had (Giving him targeting and destruction immunity from ONLY your opponent's cards). The real MVP's of the deck are Servant, Reflection, and Magister. They all share the effect that they can use three spell counters to special summon themselves from the pend scale along with another monster you can place a spell counter on from your deck (servant's effect), your hand (reflection's effect) and face up from your extra deck (magister). You'll want to put them in the pend scale now, preferably Servant + Magistus or Magistus + Reflection. Keep in mind that all three of these cards can only be special summoned once per turn (which bites you in the a** at the worst points in duels). Then use your spellbook draw engine:

The spellbook engine consists of just 4 cards, Spellbook magician of prophecy, Spellbook of knowledge, Spellbook of secrets, and Crowley, the first propheseer (in extra deck). Depending on the combination drawn, activate Secrets, add Magician, normal Magician and add knowledge, then use knowledge on magician for +2 (as well as +4 counters to all your face up MB monsters and + 2 counters to your endymion scales). Or, Magician for secrets, secrets into knowledge. You can also use crowley for the same thing, if you don't draw the right cards at the start. FYI, Knowledge doesn't work on pendulum spellcaster monsters, as they get sent to the extra deck instead of the GY, where it needs them to go in order to +2

Finally, you'll want to get all your special summons (servant, reflection and magister) and link summons done (such as apollousa, BLS, BS dragon), then pendulum summon as many negates back to your field (being Endymion and Jackal king). It's best to try and get as much usage out of your pendulum summon as possible. The Odd-eyes vortex from absolute combo is simple, Xyz summon Absolute dragon using Endymion and Reflection, then link it off for Mekk-Knight Crusadia or Apollousa, then activate Odd-eyes Absolute's effect, which special summons vortex from the extra deck for free. Don't forget about reflection's effect to bounce both one card you control (with a spell counter) and a card your opponent controls to hand upon it's special summon. This is super handy for putting either Magister or Servant back in your hand to put them back in scale after they've used their effects. Speaking of, Magister has an insane effect, that, during your opponent's turn, you can burn 3 spell counters to special summon a spell counter monster from deck... Pretty crazy!

This deck is incredibly strong, being able to butt heads with some pretty powerful meta contenders, but due to the inherent weaknesses in pendulum-based strategies, brought about by the banning of Heavymetalfoes Electrumite, and master rule 5, it's unfortunately not as strong as decks like VWs or Drytrons. Keep an eye on these cards, however, as they have unbelievable potential!