Most of the lands with Threshold are pretty underwhelming, with the exceptions of Nomad Stadium (which is incredibly bad) and Cephalid Coliseum
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Of course, the really exciting part here is the ability to double your mana from creature sources
The floor is that its a big dumb idiot that can flash in and replaces itself with a smaller idiot, but it costs 10 because everyone at the table is playing combo and control
So, what we really want to see on warp cards are good abilities triggering when the permanent enters, considering how this mechanic leads us towards playing a certain number of Flicker spells in order to access a way higher quantity of value
This is much, much smaller than the estimated print runs of sets today, which are more like 2.5 billion cards