The first time I played this card I only put two in my deck because I assumed it was like the other "Power Of"s, but you can go up to the full 3 of this one! This is only for heroes Phoenix, Cable, and Psylocke for now, as there just aren't enough psionic cards out there yet - and most of them need your hero to be Psionic to be played anyways (like Psychic Assault). But for these heroes, Power of the Mind will pay for more cards in your deck than the aspect Power Ofs typically will. Note that when when you use this to pay for upgrade abilities like those on Telekinesis and Telepathy, the resources still get doubled.