Notes & Combos
An Endymion deck does a ton of drawing, so it's very common to end up with duplicates of cards that can't be used a second time. That's why I prefer running doubles of Master Cerberus, Pot of Desires, and Mythical Institution rather than triples, and it's also why I still like the Spellbook engine.
Artemis is in the Extra Deck so that any Level 4 or lower Pendulum Monster can be converted into fodder for Spellbook of Knowledge.
Finally, Magical Abductor consistently puts in so much work. For just 3 Spell Counters (which can also come from Citadel), it searches either a high Pendulum Scale or another boss monster to Pendulum Summon, and this effect isn't even a 'hard' once-per-turn. Abductor's only pitfall is if Servant or Master Cerberus get stuck in the Pendulum Zone after being negated by Ash Blossom.