Currently, these abilities interact positively on the Lamia, contrary to the current mashed-potato descriptions. In order to make this more clear and verbally consistent, Preparation should be changed to read "At the end of each of its turns, if this unit did not attack, it has +1 DMG and +1 MAX RNG. This effect stacks up to 4 times and is reset at the end of this unit's turn if it attacked that turn." Prep only breaks if a unit attacks on its own turn, not on an opponent's turn. The current description leaves this distinction ambiguous: At the end of each of its turns, if this unit did not attack, it has +1 DMG and +1 MAX RNG. This effect stacks up to 4 times and is reset at the end of turn when this unit makes an attack." While neither description is perfect, the former at least holds up under strict technical scrutiny. Edit: A perhaps clearer and more concise rewrite that implicitly links the timing of the two triggers in a way that's more consistent with what I expect the coding to be: "At the end each of its turns, if this unit did not attack, it gains +1 DMG and +1 MAX RNG, otherwise, it loses all benefits from Preparation. These bonuses may stack up to 4 times." Another version: "At the end of each of its turns, this unit gains +1 DMG and +1 MAX RNG if it did not attack, or loses all stacks of Preparation if it did attack. This ability may stack up to 4 times."
In same vein, Sentinel apparently doesn't proc Split Personality, which would imply the ability doesn't actually produce a basic attack as it says it does.
OP updated with two additional versions of the ability text, which rewrite it more extensively than the first.