Basri Ket has a plains from Amonkhet, Teferi has an island from Dominaria, Liliana has a swamp from Dominaria, Chandra has a mountain from Kaladesh, and Garruk has a forest from an unknown plane- because we still dont know where hes from
2 Gate Guardian - Attack 3750 | Defense 3400 Possessing gargantuan stats well above most other monsters, even those near and surpassing the 3000-barrier, Gate Guardian is a nearly impossible colossus to topple, however, their summoning requirement offsets their immense battle potential
Because of the high mana cost pre-delve this dodges Counterbalance quite nicely, and the delve itself allows it to ignore Thalia, Guardian of Thraben at the cost of an additional graveyard card
When these drop rates are combined with the event only being available for two weeks, and the inbuilt stamina gauge that stops you from constantly playing you have a low chance
Of course, a lot of newer cards released during development have not been added to the game yet, but likely will be added through updates
If you like grinding a game out, watching your board rebuild itself every time somebody clears it, and slowly burying the table in 2/2 robots, the Necrons are right up your alley