Both the new sets and the new mechanics appear to have had an effect on the most valuable cards for this year
This is a massive pressure on market and especially on retailers and other for-profit actors in the market
For only two blue mana you can spit out an answer to anything your opponents play, whether they are playing Darksteel Forge, Paradox Engine, or even another counterspell
They all synergize incredibly well with Aphelia so, if she causes a rise in demand, it may be wise to buy them sooner rather than later.
I've also used him to draw a card and some life, and then folks waste some attacks to kill him because they have heightened "every planeswalker is a threat" spider sense (which doesn't work for Dovin Baan as much) and they waste some turns
You only have a limited amount of it, unless you also gain it back