Of using double hammers against diablo. Before diablo spawns, hammerdins can start casting hammers on the middle rim of the star where diablo spawns, then telestomp hammer when he spawns. This causes diablo to be hit by two waves of hammers simultaneously, doubling the hammer damage against him. If done perfectly, he will die before the last hammer from the middle rim disappears.
Nobody does this anymore :/
there's actually a new mechanic that i don't think anyone does, which is using abyss to move the enemy into the hammer (this allows every monster to be hit by the hammer rather than having people stand in the dead spots). it is actually very effective