
As it is an Intro Pack, however, there are some themes that you can see that Wizards may have stretched a bit in this Core Set, especially with the Convoke mechanic. You'll see more why this is a bit stretched at the common and uncommon level as we analyze this list.
Creatures (19)
2 Sunblade Elf
2 Selfless Cathar
1 Wall of Mulch
2 Oreskos Swiftclaw
2 Midnight Guard
2 Living Totem
2 Will-Forged Golem
1 Phytotitan
2 Siege Wurm
2 Seraph of the Masses
1 Hornet Queen
Spells (16)
1 Gather Courage
1 Naturalize
1 Titanic Growth
3 Raise the Alarm
2 Devouring Light
1 Nissa's Expedition
1 Sanctified Charge
1 Meditation Puzzle
2 Triplicate Spirits
1 Overwhelm
2 Feral Incarnation
Lands (25)
13 Forest
12 Plains

The next three creatures are cases of where Convoke goes right in Magic 2015. They are all common creatures, Living Totem, Will-Forged Golem, and Siege Wurm. Because they can be Convoked, they can be cast for considerably cheaper. Living Totem starts as a 2/3 for 3G that gives another one of your creatures a +1/+1 counter when it enters. Tapping just a couple of creatures makes it a 2-drop. The Will-Forged Golem is a 4/4 for 6, which doesn't sound great, but with Convoke it can become a lot cheaper. The Siege Wurm is a 5/5 for 5GG, but again, he has Convoke, and not much can deal with a 5/5 single-handedly.
You might think, well, why would I want to tap my creatures to cast another creature? Sometimes you simply will find that you're not attacking for a variety of reasons. Why not tap those creatures that would otherwise just sit there to bring out some more powerful creatures?
Keep in mind also is that we're talking about common-level Convoke creatures. That's pretty cool to see. It's especially exciting for new players to realize that they can get some of their creatures out more quickly than they might have otherwise first suspected.
So, kudos to Wizards on designing these creatures. But there are a couple of examples later of where Convoke isn't so playable. One comes right away in the form of the next creature on the list:
Seraph of the Masses is a cute card. It's an angel (yay) but it costs 5WW to play (wah). Oh, but it has Convoke! The Seraph has power and toughness equal to the number of creatures you control! There's a problem with this. There was a card in a past core set called Crusader of Odric. She cost 2W to play, didn't have Convoke, but did the same thing. Geist-Honored Monk from Innistrad cost 3WW, had Vigilance and brought two fliers with it.
Oh, but this Seraph has flying! Yes, that's relevant. But 7 mana is a lot for a flyer that might be a 4/4 or 5/5 when it lands, especially if you have to tap down your creatures to do so. In Limited, this can work out alright. But in a Constructed deck, even an Intro Pack, there are usually better options to play. However, she does happen to work well alongside the last creature we'll be taking a look at...

First, she has deathtouch. Secondly, she brings four 1/1 flying creature tokens with deathtouch in with her. OK, she combos well with the Seraph - that's certainly true. But wouldn't you rather have a swarm of death-touching Hornets?
All in all, I'm not crazy about the Seraph. But for an Intro Pack, it's a pretty solid creature line-up that shows off some of the better things that the Convoke mechanic has to offer.
Onto the non-creature spells, we start with Gather Courage.

Naturalize is your typical 1G destroy a target Artifact or Enchantment at Instant speed. It's been reprinted tons of times. Titanic Growth is 1G for an instant that gives a target creature +4/+4. Giant Growth is usually better, and it was still in Standard when this deck was first released.
Raise the Alarm is a great reprint from Ravnica: City of Guilds. It's a common that for 1W makes 2 1/1 White Soldier creature tokens at instant speed. It's fantastic for giving you creatures to tap for your Convoke costs, and being White creatures, they help you with your White mana requirements. There are 3 copies of it in this deck. It's a very playable card that sees Modern play in Black/White tokens, and has seen Standard play whenever it's been in the format.
Devouring Light is yet another Ravnica reprint, with awesome new artwork. It has Convoke, which means that it combines perfectly with Raise the Alarm. For 1WW, you can exile a target attacking or blocking creature. This is very strong removal when you figure that you can potentially play this card for zero mana. Very strong card. There are two copies in the deck.
Nissa's Expedition was a new card from Magic 2015. It's a sort of ramp card, allowing you to search your deck for up to two basic lands, put them onto the battlefield tapped, then shuffle your library. It's slightly better than a card like Cultivate, which lets you search out two lands, but one of them go into your hand. Five mana seems a bit costly for a ramp spell, especially at sorcery speed, but it does have Convoke. It was never great in Constructed, but has seen play in some Commander decks.
Sanctified Charge is another new card. It costs 4W for an instant that gives creatures you control +2/+1 and first strike until end of turn. This is an interesting combat trick, although 5 mana is a lot. Dictate of Heliod from Journey into Nyx is a better combat trick, and that's an Enchantment with Flash that boosts your creatures by +2/+2 as long as it remains in play. But it's not a bad common, and it's an okay Intro Pack card. The first strike is especially nice, as it can turn would-be trades into wins for you.
Meditation Puzzle is one of the Convoke cards that makes me scratch my head a little, but I see why it's in here. It's a common Instant for 3WW and Convoke that gains you 8 life. That's quite a tempo swing, and there are people that have enjoyed playing cards like Angel's Mercy - which gained you 7 life for 4 mana. It's a great Limited card, but I don't typically like it in Constructed unless you're specifically playing around a lifegain or tempo theme.
Triplicate Spirits is a Convoke card I can get behind a bit more. It costs 4WW for a Sorcery that makes three flying 1/1 spirits. The Convoke cost makes it a bit easier to stomach, though. I like this card more than Meditation Puzzle, certainly, and getting fliers is pretty cool. I do feel it's a bit slow for Constructed, though.
Next we have Overwhelm, which is basically Overrun with Convoke. There's an obvious problem with that. Having to tap down creatures to help pay for an effect that boosts your creatures by +3/+3 until end of turn seems a bit counterproductive. Plus 5GG is a lot for that sort of effect, especially when you don't gain trample as most Overrun type effects do. I'm simply not a fan.
Feral Invocation rounds out the mana curve all the way up at a whopping nine mana (8G). However, it does make three 3/3 beasts and it does have Convoke. At the time, though, the two "Surprise Centaurs" of Fated Intervention from Born of the Gods were simply more cost-effective. I would play that over this at Sorcery speed. Were it Instant speed it would be a cute combat trick in an Intro Pack. But at Sorcery speed, it's just very slow.
The list finishes out with 13 Forests and 12 Plains, for your typical 25 land in an intro pack.
"Will of the Masses" has a lot going for it. It shows off some of the cool things Convoke can do, by helping you amass forces that can do some serious damage. But the higher end of the curve is clogged up with what I feel are rather inefficient cards like the Seraph and some of the high cost Convoke cards. I like what Triplicate Spirits is doing and gaining 8 life out of nowhere with Meditation Puzzle is cute, but overall it's a bit of a disappointing finish to what starts out as a pretty cool list. The top end of the curve needs work, so I'll give this a B-minus as far as intro packs go.
The final verdict is that this may be the second- or third-best of the Magic 2015 Intro Packs, with Flames of the Dragon being the best of the bunch. For awhile, though, when Hornet Queen skyrocketed in price, this was the most valuable.