if(CustomBlockAgainst.getClass() == me.bootscreen.customslabs.slabs.EndstoneSlab.class)
{
    BlockBreakEvent blockbreakevent = new BlockBreakEvent(BlockAgainst, event.getPlayer());
    plugin.getServer().getPluginManager().callEvent(blockbreakevent);
    BlockAgainst.setType(Material.ENDER_STONE);
    event.setCancelled(true);
}