Sennachie's Boon

As Sennachie's Boon enters the battlefield,
choose a creature type.
At the beginning of your upkeep, look at the top
card of your library. If it's a creature card of the
chosen type, you may reveal it. If you do, target
creature you control of the chosen type gets
+1/+1 until end of turn for each other creature
with that type.
"Our ancestors will guide you..." -Digenia, Sennachie