Beware the Ides
From Archon Arcana
Beware the Ides • Saurian • Action • Common • Play: Deal 23
to a creature in the center of its controller’s battleline. • Artist: Nicholas Gregory • Card Number: MM (184)

Commentary
There is only a center of a battleline if there is an odd number of creatures in that battleline. When there is an even number of creatures in a battleline, there is no center. If there is only one creature in the battleline, that creature is in the center.
Source: Center of the Battleline