I currently "live" in a Ice Plains Spikes biome and I need to terraform a big chunk of area full of ice spikes. What is the best way to destroy (not collect) packed ice blocks?
After doing a lot of research, at the moment there is no true tool to destroy packed snow. While the Minecraft Wiki says
They can be obtained using any tool with the silk touch enchantment.
It doesn't say the speed about any tool.
In relation to Ice the efficiency 5 pickaxe would be the way to go. But According to the Mojang Bug Report Site that does not work that same way. Based on what Carl Lystad said :
I would say Works as Intended, as efficiency only applies to blocks that the tool is normally faster at breaking. Packed Ice, like regular Ice, does not have a specific tool that is faster at breaking it, so efficiency will have no benefit. Efficiency was changed back around 1.5 (I forget the exact version that changed it, but I think that's right) from its previous behavior, which would have produced the effect you are looking for.
I believe this anwsers your question. Also Ice Plains Spikes Biome.