Commander play is more likely, possibly even in the command zone, but there are a lot of better, easier-to-cast options out there
Demonstrate has not been widely used in EDH precons, and there are only a few cards with the keyword
(2017-08-25) If a creature has been dealt damage, that damage remains marked on it until the cleanup step
Yes, the white cards that draw you cards when your opponent casts spells cover the full range of only use in special cases to format staple. The best such card is Esper Sentinel, which requires opponents to pay mana to cast noncreature spells or you'll draw you a card
Effect Veiler Effect Veiler Spellcaster TunerEffect C Common UR Ultra Rare QCSE Quarter Century Secret Rare C Common SR Super Rare UR Ultra Rare SE Secret Rare UL Ultimate Rare PS Platinum Secret Rare CR COLLECTOR'S RARE QCSE Quarter Century Secret Rare C Common C Common STAR Starlight Rare UR Ultra Rare C Common C Common C Common UR Ultra Rare (Duelist Saga Version) C Common PL Platinum Rare C Common GR Gold Rare SR Super Rare R Rare UR Ultra Rare UL Ultimate Rare
Of course, it takes three different Xyz monsters to make, so it had to be worth it