Brotherhoods End is a wrath that just keeps earning its keep for me in every game I play it
The card drew criticism because it is very powerful and mechanically unique, but was only on sale for a limited time and depicts a character who is very much not a part of the MTG Multiverse
Although the token is attacking, it was never declared as an attacking creature
It's cheap and splashable so it can easily slot into any Blue deck, but being an enchantment makes it particularly juicy in Enchantress decks like Zur the Enchanter and Tuvasa the Sunlit, and in Blind Seer decks which run cards like Glamerdye so you can change Insight to trigger off whatever the most popular color is that your opponents are running
League Guildmages second ability is entirely dependent on having a cheap and powerful spell you actually want to copy, like Lava Coil
For example, a 1/1 creature that enters under your control "with a +1/+1 counter on it" won't receive an additional +1/+1 counter
