P109 : Iron Forest Style Description: A bushi versed in the spear can control their spacing with their opponent very efficiently, forcing their foe to risk impalement each time they advance or catching loose clothes or stray body parts on the head of the weapon. Akodo’s Leadership refers to such a technique as the Iron Forest style, turning the length of a single spear into an insurmountable gap for a would-be attacker. Prerequisites: School rank 2 XP Cost: 2 Activation: When you make a Martial Arts [Melee] check using a spear, naginata, or other polearm, you may spend in the following way: : One target of your action becomes pinned until the beginning of your next turn. While pinned, if the target attempts to move closer to you, the target must resist with a TN 4 Fitness (Air 2, Water 5) check . The target suffers physical damage equal to their on the check. If the target fails, they cannot move closer.
What does that exactly mean: "TN 4 Fitness (Air 2, Water 5)" is it a TN 2 if i use air , or is it TN 2 if opponent resist with air?