The Gusting infusion can be given a duration of 1 round for either a cost of 2 Burn or having the blast do no damage, and the Wall infusion has an innate duration of 1 round per point of the Kineticist's Con modifier--so what if you combined the two on an air blast and chose to have it do no damage? Would that result in an air wall that forces a DC 15 Strength check to cross it (as per Gust of Wind) for the wall's duration?
You can combine one form infusion and one substance infusion on any blast without issues. From the Kineticist's Infusion ability:
By using infusions along with her kinetic blasts, a kineticist can alter her kinetic blasts to suit her needs. Infusions come in two types, each of which changes a kinetic blast differently: a substance infusion causes an additional effect, while a form infusion causes the kinetic blast to manifest in a different way. Each infusion can alter only certain kinds of kinetic blasts, which are listed in its Associated Blasts entry. Each time the kineticist uses one of her kinetic blast wild talents, she can apply up to one associated form infusion and up to one associated substance infusion.
If we check the Gusting infusion, we will see it is a substance infusion:
Element(s) air; Type substance infusion; Level 1; Burn 1
While the Wall infusion is a form infusion:
Element(s) universal; Type form infusion; Level 5; Burn 3
Since both infusions can change the damage of your Blast (if you accept extra Burn from Gusting), you have to apply the substance infusion first, then apply the form infusion. Gusting reduces the damage to 0, and form reduces the damage to half since Air generates physical blasts (but 0/2 is still 0).
If a kineticist’s form and substance infusions both alter the kinetic blast’s damage, apply the substance infusion’s alteration first.
This means you have three options:
- An instantaneous blast that will hit a single target for normal damage and hold/push him away. This costs 1 Burn.
- A lasting wall-shaped blast that causes half the damage of your blast and will hold/push enemies away from it. This costs 4 Burn.
- A one-round lasting line-shaped blast that causes no damage but will hold/push enemies away. This costs 1 Burn.