With two cards acting as complete blowouts with Grief, its important to understand that getting stranded with one or two of those effects for a turn or two is fine because they allow for some huge turns that will leave the opponent scratching their head
The fact that the deck has two commanders also ups the power level quite a bit because you essentially start the game with two extra cards in hand and fill two spots on your curve
Supplant Form looks mixed since it has a strong effect, but 6-mana is steep
The Blightbeetles are an obvious nod to Mono-Green Devotion and Hardened Scales, which, based on the mad search for Vivien, Arkbow Rangers that played out on Twitter leading up to the event, I expected would be quite popular
When that spell or ability resolves, Abrupt Decay won't be countered, but any additional effects of the countering spell or ability will still happen
We've already been shown one instance of Saga mechanics at play on a Creature card through the example of Summon: Shiva