Buy these leg greaves, wear them, don't die from spike thorn.

Each pair has 95% nature resistance and 50% puncture resistance. Spike always starts at the legs (if you're standing) so with leg greaves along you can usually always survive.

Should last 400 spikes, so if you got them just for invasions or dueling, should last a long long time. If you got them for a specific critter, like shan, should last as long as you hunt them.
The above shop has normal plain ones, 500k each
The above shop has a special pair that also has offensive spikes, 2m