His second ability is a bit underwhelming. For 2RW you get a 1/1 red and white soldier creature token with haste onto the battlefield. Now that 1 damage may be enough to put the game away, but for 4 mana, especially in Boros, you will have better options. Heck, just play a Lightning Strike for 1R if the game’s that tight!
Overall, Sunhome Guildmage may be an OK card in Limited, but in Constructed he’s one of the weaker Guildmages. He’s not even really great in Commander, unless you find someway to get ridiculous amounts of mana to pump your creatures for a game-winning alpha strike. While that’s doable, there are far better combos. Then again, if you can find a way to get that sort of mana, you could also get ridiculous amounts of tokens. It’s something to think about, but again, there are far more efficient cards that can do these things than this can.
Her casting cost is far from the best part about her, as her activated abilities are just plain silly. For 1R, you can give target creature haste until end of turn. We’ll use a good example from Commander. Say you play a Balefire Dragon or something else big that doesn’t have haste. Well, for 1R, it now does. In the case of Balefire: goodbye, opponent’s creatures – as Balefire deals damage equal to his power, usually 6, to all of that player’s creatures. There are plenty of creatures that you would not mind paying 1R to have haste and swing for great effects or for game. That ability is just fantastic. You can use that ability on Guildmage herself, although you probably wouldn’t.
Her second ability, while more tactical, is also incredibly good. For 1W, you can give a target creature first strike until end of turn. This can lead to some interesting blocking situations. If you have the open mana, some players simply will let your attack through because giving first strike a lot of times will kill their creature and not yours. It’s also a fine combat trick for when they do block. While not quite as exciting as giving something haste, it’s a great ability that can serve you probably just as well.
The only issue is now that Boros Guildmage isn’t in Standard. I don’t know if any Modern Boros lists will ever be running her, considering how easy it is to remove her. In Constructed today, while those abilities are pretty darn good, you won’t often use them until much later in the game since they are what players like to call “mana sink” abilities. The best application for her is in Casual Boros decks and in Commander, where you often have mana to spare on many turns, and giving things haste in Commander can be a potential Win Target Game depending on what creature you’re giving it to. So she’s a really good card to have.
So while neither Boros Guildmage is especially fantastic in Constructed, there’s little doubt that Boros Guildmage wears the crown for better card here. Sorry, Sunhome Guildmage, you’re just not quite good enough, although you can make a whole bunch of tokens…