Eruzerion

Trample, hexproof.
If a creature under your control were
to deal damage this turn, creatures you cast cost {u/r} less to cast, and have flash this turn.
For each {u/r} spent with {r} when casting
Eruzerion, Eruzerion gets +1/+0 permanently.
For each {u/r} spent with {u} when casting
Eruzerion, Eruzerion gets +0/+1 permanently.
You can cast Eruzerion's {u/r} cost with both colors
each. If you do, Eruzerion taps target five
creatures, and fights target creature.