редстона не вижу
if(flag)
{
int l = world.getBlockMetadata(i, j, k);
if(l == 0)
{
world.setBlockWithNotify(i, j, k, Block.obsidian.blockID);
} else
if(l <= 4)
{
world.setBlockWithNotify(i, j, k, Block.cobblestone.blockID);
}
triggerLavaMixEffects(world, i, j, k);
}