As Pramikon is a wall itself, it naturally synergizes with various wall-tribal cards and toughness-based synergies whilst providing access to three colors worth of high-toughness creatures
This card would be ridiculous without the whole otherwise put it in your hand caveat
As the blue member of the cycle, it offers a free counterspell that delays creatures or planeswalkers without ever spending mana
A Flash counter and or blocker, there's some very fun way to use this, especially during things where your opponent may assume they're safe to be greedy, such as on a turn-ending before untapping fully, and I agree with Loxi: players like to tap out a lot carelessly
Riot Control Its a little expensive, but Riot Control is still acceptable if youve got some lifegain synergies
With the release of top notch delve cards from Tarkir, the delirium mechanic things, flashback stuff, recursive dorks, and even just an increase in good graveyard recursion effects there is a significant increase to the value of self mill