Basically, according to Wizards ' own thoughts back in 2015 and the consensus view of the community, the London mulligan rule seems likely to power up two of the most problematic and least liked aspects of the Modern format, and this doesn't even take into consideration that certain cards or decks can directly abuse the rule (most commonly cards or combos that actually want you to have fewer cards in hand, like Restore Balance or Ensnaring Bridge, both of which happen to win by making the opponent unable to play a full game of Magic or, in the case of Restore Balance, any form of Magic at all)
When Karazikar attacks, you get to tap a creature and goad it, removing it as a blocker against Karazikar and forcing one of your opponents to take the attack in a few turns
Disney notes that quantities are limited each day, so you'll want to stop by the World Showcase Bridge and get one as soon as possible
The hype for the ever-closer-to-release Final Fantasy set is just on another level
And if the card could have been a lightning bolt, you are actually back -13 and a couple of mana