At 7 mana for a 1/1, you wouldn’t ever see this played in Standard, or really any other competitive Constructed environment. But, for an uncommon, getting 4 bodies in one card is definitely a powerful ability. When Trostani’s Summoner enters the battlefield, you get a 2/2 Knight token with vigilance, a 3/3 Centaur token , and a 4/4 Rhino token with trample. The 1/1 body itself isn’t all that relevant.
However, in decks that play token doublers such as Doubling Season, Parallel Lives, and Primal Vigor, you’re suddenly getting 7 bodies with one card. With Populate effects from Growing Ranks, Trostani, Selesnya’s Voice, Vitu-Ghazi Guildmage, and more, Trostani’s Summoner’s little 1/1 body becomes a lot more important. Seven mana isn’t much for Green decks to muster quickly, so getting that many creatures into play at once can be devastating.
Certainly, back in its time, Trostani’s Summoner is a card that could be a huge swing in a draft. Seven mana for four bodies is pretty difficult to deal with in any Limited environment. Of course, today, this Elf Shamans only sees play in Commander. Unsurprisingly, she’s become pretty much an auto-include in Elf-heavy token EDH decks such as Emmara Tandris, Tolsimir Wolfblood, and the very popular Trostani’s, Selesnya’s Voice.
The other type of deck that can take great advantage of Trostani’s Summoner is a “blink” type deck. These decks, often led by Roon of the Hidden Realm, can exile a creature you control and return it to the battlefield at the next end step. Abusing the Summoner’s enter the battlefield ability is not hard to do in that sort of deck, especially when you can do so on the end of your opponent’s turn. That means your tokens will then be able to attack on your turn.
It could be argued that Trostani’s Summoner is actually underplayed when you consider her utility. Of course, she is a seven mana card, and you typically want something more impactful at that point in the mana curve, even in Commander. But, she is a well-designed card that definitely has her value in the right strategies. Don’t overlook her. Plus, the extended artwork is fairly impressive. If you are running a deck that plays a lot of tokens in Green and White, this Elf Shamans is worth a second look.