It is format changing because it makes cards like Gengar Prime, Palkia G, Absol G, and others playable
Tag Call allows you to search out not one, but two Tag Team cards, of which can even be the same one
Of note, these arent bonus sheets but they are subsets, though they lack their own set code, like BIG and OTP were for Outlaws of Thunder Junction
Opening expansions with new player cards is particularly exciting for the Ritualist, especially when their investigator has experience to burn
The engine is very small, with Invocation being a card you only really need to run one copy of
(The tokens also make some nice targets for Enemy Controller) The biggest disadvantage this card has to the other two is being on the same attacking level as Reborn Tengu, which is a little unfortunate but can be worked around with Spell and Trap support that manipulates Attack and Defense, one in particular is Honest