Youre just never safe if your opponent has this in play
Spells with cost discounting abilities (like delve or spectacle) or those with additional, non-mana costs can let us double a much more expensive/impactful spell than we normally could afford
So, if you have them both in play, Sephiroth can sacrifice Aerith for his fourth trigger, transforming, and then reap the benefits of all the +1/+1 tokens Aerith had built up from his attacking
This spell simply allows you to choose new targets for a spell or ability, which means you can redirect a lethal spell, a nasty planeswalker ability or even something just mildly inconvenient
I played as a purely casual player for a couple of years when I first got into Magic , and while we had free mulligans and no clue about formats, we still wouldn't let people play with silver-bordered cards
Mason gives very detailed instructions for each turn