Rift Walker

When Rift Walker enters the battlefield, create
a Temporal-Rift token. (It's a blue enchantment
with "{2}, Sacrifice this enchantment: The next spell
with mana value 2 or less you cast this turn can be
cast as though it had flash.")
{1}, Sacrifice a Temporal-Rift: Choose one —
• Rift Walker can't be blocked this turn.
• Rift Walker gains double strike until end of
turn.