Guardian Angel Help (in General)

This is probably a case of me missing something obvious but I cannot for the life of me figure out why my GA doesn't backlash against Decay in this particular battle.

The odd thing is if I have a different minion out front it does backlash damage.

GA doesn't do backlash damage to PL minions. Because they are not taking any damage. The pl is absorbing it, so It doesn't count.

Yup, painfully obvious.

Thank you for the help, it is appreciated.