[Chaos]

To be honest, while the effect can be pretty serious for something that only has one specific tile it can be entirely bypassed on, Stalemate also requires the following conditions:
1. The incoming action is an 'attack' (see: precisely like Normal Attack)
2. The weapon used in the attack is a sword, a spear, or an axe
3. The RNG rolls somewhere between the minimum value and (Rank*5)+(DEF/2)

Given these conditions, I think forcing Stalemate to adhere to Snake Dancer's 'within vision' restriction would be a little too much for an effect that only occurs for a specific portion of offensive actions, much less one that also requires RNG to trigger. Maybe if it had a buff to equally compensate, perhaps.