Unless you have a sacrifice outlet, you will have to wait until one of your non-Angel creatures dies to tranform this card
In a four-player game, that's up to three casts, but there will always be one with just creatures or land, and another with no hand at all, and then another with unplayable reactive stuff like Counterspell
Only check regulation marks if youre building a competitive deck
In the reprints corner, Massacre Wurm can be a painful threat, while Phyrexian Scriptures shapes up as a one-sided board wipe.
You can presumably cast anything you find off it since you already had the mana to cast the Mage, which could include mana rocks like Chromatic Lantern and Worn Powerstone, or disruptive pieces like Trinisphere and Static Orb
Right now, in Modern, the plan of cascading into a zero-mana-cost card is extremely popular