So firstly the look, Summer is not about subtlety, it is about Majesty, things are about being larger than life in the Summer Realm. So take the opportunity to be bold and daring, Heraldic crests, staffs with mythical creatures on them, absurd over dagged mantles. If you aren’t Dawnish, have you considered being Dawnish. More generally have a brand, be proud of it turn and it up past 11.
Now part of me just wants to say Knights of Glory, and just leave but putting aside my characters biases.
Most of Summer comes down to either Battles (buffing your mates to fight better) or War (Impacting the strategic Campaign.)
Technically Summer has the easiest ritual to impact the military campaign in Clad in Golden Rainment, which buffs military units although Raise the Banner of War gives you a lot more bang for your mana. You can also turn mana sites into giant flaming animals (This is paying 2 mana for added coolness over the Day ritual, but it is very cool.)
Summer also has 5 of the big strategic rituals, however the fort enchantments are very situational, as it’s not that often there are forts to cast them on. Ice Castles are far more reliable aim if you can hit them.
Summer has a huge set of personal buffs ranging from some of the cheapest enchantments, to high end luxury enchantments. Generally I would say that past Sound of Drums you are likely to find less takers (ignoring Panoply as a group enchant.) but take what your group or nation will benefit from
Of special note is grant shield use because it’s a great make someone more useful in battle buff.
Challenge the Iron Duke
Yes this is it’s own category of rituals, because it’s worth it. There are a bunch of Day and Winter rituals which are really cool because they let you chase plot better, this makes plot come to you (or your mates) and also gives you some input on what the plot is.
Summer has a some interesting Priest buffs, including empowering them to improve ceremonies, and hero point restoration in a courage aura, which could be an interesting side spec for a sect if you have a mana site.
There are some economic rituals, but there are better realms for both fleet and mine buffs. Oh, and you can bother Meraud with magical messages.