I know I’m almost two years late on this post, but I recently started playing an arcanist for the first time and was curious about how this ability works. After reading this post and thinking it through, I have to conclude that, despite the way it’s worded, it should be 1d4 with an additional +1/level. Here is my reasoning. If we accept the max for this ability is reached at 20th level that would mean that for 1 arcane pool point you have an attack that auto hits for 21-24 damage, which is a good amount. However, if you go with the (1d4+1)/level you would be hitting, automatically I remind you, for 40-100 damage for the same 1 pool point, of which you could have up to 23 or more at level 20. That single ability out strips the damage potential of ninth level spell, and costs virtually nothing to do so. That is beyond broken and very unlikely something Paizo would have over looked or intended to be the case. As a DM you would either have to plan every encounter to have protection from magic missile or have a single PC who can potentially defeat any encounter you throw at them in a few rounds. Even some extremely tough creature with 400 hp isn’t going to last very long against that level of auto damage. If there is a DM letting it play that way I feel so bad for you:)