"Speak little. Do much."
What if Young Pyromancer was legal in Standard, now?
After all, Young Pyromancer is one of the most powerful creatures in Modern, Legacy, and Vintage. It could find a home in a Standard that features decks like Jeskai tokens, right?
Sure! That sounds great!
Now, what if the new version in Fate Reforged was better...?
Fate Reforged has some really awesome cards. Monastery Mentor is one of them. Here, take a look:
Monastery Mentor's flavor text is absolutely perfect at describing the impact the Mentor has on the game. On the surface, he looks calm and ready; but the game has a tendency to absolutely explode, when unchecked for even a turn or two.
Monastery Mentor is a Young Pyromancer with four important upgrades, in exchange for costing a mana more (and being in a color that doesn't abuse it quite as easy). Each of these upgrades is important, but the cumulative effect is absolutely devastating and why I think Monastery Mentor is even better than Young Pyromancer would be in Standard.
The most important upgrade over Young Pyromancer is the difference in tokens. No, not Monk versus Elemental. Monastery Mentor's tokens have prowess. That is huge! Giving a single 1/1 prowess is good, but not necessarily stop the presses good. However, this is not just an entire army in one-card, it's also the greatest Anthem you could ever hope for. What's better than making three 1/1s? How about attacking for 17 the following turn!?
The crazy amount of damage possible by Monastery Mentor is due to its abilities scaling exponentially! Every non-creature spell you cast doesn't just pump it by 1 (like every other prowess creature). It makes another creature that will attack for 1, next turn. Ok, so now you're getting paid double right? The thing is, cast another spell next turn, and you're getting paid triple, since both of your creatures get pumped and you get another token (that will also pump in the future).
What's the practical impact? This is the Hordeling Outburst and the Jeskai Ascendancy. It gives you the army and the Overrun. You're regularly going to be attacking for 17 or more in a single turn. That is basically unheard of from a three-drop, and that's to say nothing of combining it with Jeskai Ascendancy or Jeskai Charm.
Speaking of Jeskai Ascendancy, it's important to remember that Monastery Mentor triggers off of it (as well as Chandra, Pyromaster and Elspeth, Sun's Champion). Young Pyromancer only pays you for sorceries and instants, which makes for another sizeable upgrade in Standard. It's not just an extra token or two we're talking about. Each trigger also AOE pumps your team, so it is very important to get the absolute most we can.
Another important advantage that Monastery Mentor has over Young Pyromancer is that second point of toughness. That might not seem like a big deal, but it's actually huge. One of the best ways to fight Young Pyromancer is with cards like Electrickery, Izzet Staticaster, Orzhov Pontiff, and other spells and abilities that deal one damage. Unlike the Pyromancer, the Mentor can actually live through these hate cards and start building a new school immediately. Think about how much that second point of toughness matters when your opponent plays a Doomwake Giant!
Of course, the dream is to hold up an instant so that when they Doomwake Giant, you don't lose your students either. However, it's nice to have a back-up plan!
Yet another advantage Monastery Mentor has over Young Pyromancer is its prowess ability. This may seem minor compared to the awesome power of an entire school of monks descending down on your opponent, but it's actually quite good because it lets the Mentor itself get into the red zone more often than Young Pyromancer ever did.
Generally, Young Pyromancer is staying back and watching from a distance, only attacking when the coast is clear. Monastery Mentor can attack, force your opponent to decide how to block, then get huge in combat. Even if they triple block in combat, you might Lightning Strike one blocker, Magma Jet another, and outclass the third! Besides, it's not like they can always just block with all of their creatures. What about all the Monks you're sending in? If they block the Mentor with too many, maybe just send the burn spells upstairs and make it twenty to their face with the help of all that unblocked damage!
Monastery Mentor is the epitome of "must kill," but prowess can actually make this surprisingly difficult sometimes. Drown in Sorrow is a popular way to try to fight token makers (like the Mentor), but if you have even a single instant, he'll live through it. Of course, if you can pull off two, most of the tokens will even live!
Not every deck is going to be able to threaten two instants to protect the Mentor from Lightning Strike and Bile Blight, however, both Jeskai Charm and Jeskai Ascendancy make this a one-spell situation.
Monastery Mentor makes your token makers more effective (Raise the Alarm and Hordeling Outburst are effectively +1), which makes your AOE pumps more effective. But, it's not like Monastery Mentor can only go in Jeskai…
In W/U Heroic, you can actually protect the Mentor very easily and let loose with a rapid flurry of noncreature spells in the same turn. Two turns in a row and they're dead.
This might be what W/R Heroic needs to make a comeback (as Phalanx Leader has some potent synergy). It might even be enough for W/B to become a top tier contender (as Read the Bones is great at fueling repeated prowess triggers, and W/B has tons of good proactive spells worth playing anyway).
U/W Control? Monastery Mentor completely takes over the game and is especially devastating to people that aren't playing much removal (such as people sideboarding against U/W Control!)
It can actually play defense.