Aren, Yawë Signet of Brom

{t}: Add two mana of any one color.
{u}{3}{t}: Proliferate, then power-store. (As long as
you have two untapped lands, you may put an energy counter on this artifact.) Only activate this ability
on your end step.
For every five energy counters on this artifact,
spells you cast cost {1} less. If there are fifteen
energy counters on this artifact, creatures you
control gain ward {5}.