Depending on how your local game store handles things, you might have to specifically sign up to attend or just show up on the day, but typically participation sees you purchase a special pre-release pack which will give you a life counter dice, six booster packs from the set, and a special promo card
When that spell or ability resolves, Koma won't be countered, but any additional effects of the countering spell or ability will still happen
Kindred Charge can also be useful, especially since youre going to exile your token copies anyway
The Twelfth Doctor himself leads the charge here, letting you demonstrate the first spell you cast via suspend, unearth, rebound, etc
There's so much looting and rummaging that you get to churn through your deck quickly, reducing variance and making sure you find the cards you need (and discarding the ones you don't) reliably, WITH ONE MAJOR EXCEPTION (see The Bad) It's very consistent