While the TCGplayer market price is lagging, look for sales to exceed the $200 plateau when you're reading this
Here's how to pick, the top five, and the math behind it
its indeed spellbook is one copy per turn but not at star hall, starhall is +counter (if you suggesting citadel), +atk, and +add, just destroy it with MST or heavy storm when it has counter (3 is enough) then add exodia with this eff, 3 star hall is +3 i think, first i used citadel, but when i used it, library only can use citadel's counter once per turn even citadel has more than 3 counters after first use(maybe bug, and i've deleted my replay, i'll test it again and post the replay if i has same problem again), so i changed with tower, i'll test what your suggest tho, coz i want improvement (fastest now is 4 turn exo), so why not
On top of that, it has a three-Energy attack called Eon Blade that deals 200 damage, but it makes Latias Ex incapacitated to attack on the next turn