Explosive rune

The spellcaster create rune anywhere within 4''
and line of sight. If any character or creature
that was not part of the spellcaster’s warband
at the start of the game moves within 1''of the rune,
it explodes, and every figure, friend or foe, within
2'' suffers an immediate +5 magic attack.
It does not explode immediately, figure must move
to set it off. A spellcaster may have three such
runes. If the spellcaster that placed a rune
is no longer present, roll a die, at the end of each