Planar Alliance

When Planar Alliance enters the battlefield, put
a loyalty counter on each planeswalker.
Each planeswalker enters the battlefield with an
additional loyalty counter on it.
{5}{w}{w}{w}: Proliferate. (Choose any number of
permanents and/or players with counters on them,
then give each another counter of a kind already
there.)
The Phyrexian invasion of the multiverse forced Planeswalkers to put aside their differences and fight
side by side.