Yellow is Amber, Green is Emerald, Blue is Sapphire, Purple Amythyst, Red Ruby and Silver is Steel
You move the stats around a bit and add in the ability to make a second 3/3 on the following turn and it's pretty clear how much of an upgrade this is
Try to follow along at home
Brawl Legal Vintage Legal Timeless Legal Commander Legal Pauper Not Legal Oathbreaker Legal Penny Not Legal Toolbox Buy This Card Notes and Rules Information for Esper Sentinel: If a noncreature spell was already cast by an opponent the turn Esper Sentinel enters the battlefield, that opponent already cast their first noncreature spell this turn, and Esper Sentinel's ability won't trigger for that opponent that turn
Anytime she attacks an opponent, you get to put either an Angle, Demon, or Dragon creature from your hand into play, tapped and attacking that same opponent
For just one red and one generic mana, you get a 2/1 Legendary Creature with a whole lot of text