how did mr.d save Percy's life through and iris message again? i forgot

What happened was that Percy contacted Mr. D. door an iris message and he begged for help. Mr. D. then worked some god-magic and grew a bunch of wine vines to tangle up the advancing monsters. THe help did not come through the iris mesage, As gods are in many places at once (so to speek) he was able to work his power over to Percy. I hope this helps!