Thaumic Spikes are a block added by Thaumic Bases. It is an upgrade to Iron Spikes and will inflict 14 () points of damage to mobs that come into contact with it from above. When the Spikes kill a mob they will become bloody and can be wiped off with Enchanted Fabric, which will turn it into Bloody Enchanted Fabric.
These Spikes will not destroy items. They can be rendered harmless with the presence of a Redstone signal.
You have managed to improve your spikes using that thaumic metal - Thaumium. Those new spikes are sharper - they will kill fools who step on them faster than the mundane iron spikes. They are also much more picky when it comes to damaging foes - they will not destroy items. They are also sensitive to Redstone signal, and therefore will not damage anyone if they are powered by it.