You must announce the method of payment for the spell when placing the spell on the stack
Excadrill ex $26.43 A Bright Future Ahead Excadrill might not jump out as an obvious choice to include as a Special Illustration Rare in Black Bolt, but since both White Flare and Black Bolt had to share Pokemon from the same Unovan pool, it inevitably meant some underdogs would get extra love
I think the main use is to give protection from a removal spell for 2 mana, which I believe is a filler combat trick or mostly a sideboard card
Having a card thats incredibly good in Limited is usually a sign that it will be good enough for Constructed as well, although its not always the case
No other card puts study counters on cards in exile, so youre entirely reliant on the tap ability, which isnt even guaranteed to put cards into exile
Top 10 Iconic Spell Cards in Yu-Gi-Oh