Yuna is a must-kill threat on a lot of boards, and it should be easy to set up since white and green have some of the better summons
Ruling the roost: The best MTG commanders It may cost an eye watering nine mana, but if you're able to get it out on the field the game and protect it, The Ur-Dragon is hard to beat
The biggest weakness is any Stifle effect, unlike Lab Man and Jace you wont be able to just try again by drawing a card you would need to flicker Thassas Oracle or some other method to try again
But EFs have also led to a variety of MTG Arena features, both big (achievements, having cube drafts at all) and small (the big "this creature has reach" icon)
So the price change is all based on people wanting the new borderless instead of the old
Umbreon Gold Star (POP Series 5): One of the most desirable English-language cards outside the Base Set