[Oyster.]

Every sustain spell is mathematically weaker than non sustain spells. This is because sustain can't crit, and doesn't benefit from +ap. The benefit is that sustain auto hits.

Therefore there are two ACTUAL issues:

Zoning abilities (mandrakes with mud?!) and DR stacking that make approaching healers difficult

.. and skill issue

no amount of downvotes will wipe away your tears