Evaluating a function as part of Yanfly's Barrier script

[Traejeek]

For a character in my game, I've got the following notetags and an idea of what I want them to do but I can't seem to get the syntax down. It appears that the function Yanfly set up doesn't allow me to use math.pow(x, y) so here's what I've got:

<Custom Barrier Regen 1 Turns>
value += (user.lvl * user.lvl) - (0.958 * (user.lvl * user.lvl)) + 4;
</Custom Barrier Regen 1 Turns>
<Custom Barrier Points 1 Turns>
value += (user.lvl * user.lvl) - (0.958 * (user.lvl * user.lvl)) + 4;
</Custom Barrier Points 1 Turns>

The goal was a modified exponential curve with a base of 4 that scaled with actor level. However, I'm currently getting no barrier. (In a previous iteration I actually managed to accidentally get a static 6 per turn with some spaghetti that wasn't proper js).

Thanks in advance!