Ive also reached out for comment from The Pokmon Company, and will update this article if any provide statements
How many Pack Points does it cost to craft Heatran
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
For a game like Pokmon , the more, the merrier, so no two battles end up feeling the same