Tam, the Possibility (Borderless) [Reality Fracture]

Planeswalker spells you cast cost {1} less to cast.
{W}{U}{B}{R}{G}, {T}: Proliferate X times, where X is the number of planeswalker types among planeswalkers you control. (To proliferate, choose any number of permanents and/or players, then give each another counter of each kind already there.)