Blue decks usually have more cards in their other colors but still have significant blue mana needs since most of the best blue cards require two colored mana (Mana Drain, Braingeyser, Control Magic, Mahamoti Djinn), so mana balance can be a problem
It targets an opponent, so you cannot target yourself (even if you despise yourself, you are still not an opponent to yourself) or your teammate, for instance in 2HG
It reminds me of Kiki-Jiki, Mirror Breaker, but a little more balanced and has access to white, so you can play cards like Village Bell-Ringer, which go infinite with Ashnods Altar
It breaks some of the most important rules of MTG , and its introduction in serious games would dramatically change 99% of MTG encounters