Valakut, the Molten Pinnacle's triggered ability has an "intervening 'if' clause." That means (1) the ability won't trigger at all unless, at the time a Mountain enters under your control, you control five or more Mountains other than that new one, and (2) the ability will do nothing if you control fewer than five Mountains other than that new one by the time it resolves
Id say it should be pretty high on your list
Vorel of the Hull Clade Some cards on this list are tools for engines, such as the aforementioned Summoner
After over a decade without them, Owner's Pokemon (now named Trainer's Pokemon) have finally returned in the ninth Scarlet & Violet expansion of the Pokemon Trading Card Game
Every booster is a surprise, but Unlimited packs can contain some of the most famous cards ever printed, including
Well, all of this came to a head in 2011, with Innistrads introduction of double faced cards and the Transform mechanic