How much does Break Out cost
Having access to hard-lockout condition is a great way to give yourself a chance in any matchup, plus you can close out the game quickly by turning it into a 6/6 with Karns less-talked-about plus ability
That said, decks with efficient answers like Kelsien and Aminatou have the tools to keep her in check if they survive the early game
In the case of the current Standard format, Energy acceleration is more varied and prevalent than its ever been in the history of the game, and draw power is at such an extreme that setting up otherwise costly attackers is relatively easy
For just 1 Energy, it not only does 10 DMG, but also draws a card for you
This will become more apparent with a concrete example, so lets get into one