I was sniffing around tf2 files, and found out the spell (vgui\spellbook_stealth) and so on for every spell, it have came to my conclusion that this map has a script, that plays sounds, and has trigger to execute these spell huds. The folder of sounds is named Halloween_Mann_Brothers within .vpk files.
I think the "filter_tf_player_wearing_item" with the index of spellbook adds vgui to hud,
hence why no spellbook shows in hud when the spellbook is not equipped,
and also decompiling tf_weapon_spellbook gave me
http://justpaste.it/dhzd
The fun part is, that the script is not included in the map file itself,
but somewhere within tf2 folders/files,
hence the name change of custom maps to event map triggers sounds and spellbook.