Level 1: A maximum of 1 spike can be summoned. Each spike does 3 times 4+10 damage. Level 2: A maximum of 2 spikes can be summoned. Each spike does 3 times 8+20 damage.
i don't understand when they say the damage is 8+20, etc...
Hell Spikes works fine, just the warrior's expertise skills with a set damage range are broken (any speed bonus is applied, damage is not). Expertise with a percent damage bonus do work.