Fblthp, The Totally Lost

All "lost" creatures get +1/+1.
Whenever you cast a "lost" creature you may put a found counter on it, if you do put a +1/+1 counter on that creature.
Creatures are not "lost" creatures if they have a found counter on them.
If Fblthp has a found counter on himself destroy all lost creatures you control and deal damage to any target equal to the number of creatures destroyed this way.