- When an investigator/assassin studies a foe for the purposes of the special ability studied combat can this time spent studying a foe also count as time spent studying a foe for the purposes of the special ability death attack?
- Is there a feat or something that changes the investigator's studied strike so that it's, instead, sneak attack?
Studying for a death attack takes three consecutive standard actions, and studying for studied combat takes a move action, so studying for both can technically be done side by side in the same round.
There is no feat that allows treating studied strike damage dice as sneak attack damage dice. There are feats that specifically improve studied strike and studied combat, however.
1) By RAW you can't use the "studying" part of the Death Attack to trigger Studied Combat. Let me explain the reasons why:
- Mechanically Different:
In order to use Death Attack as an Assassin you need to study a target for 3 rounds, with the actual action each round dedicated to studying the target being a standard action. In order to use the Studied Attack of an Investigator you are required to use Studied Combat. Studied Combat requires a move action and lasts for a number of rounds equal to your Int mod.
Say that you could use the "studying" part of Death Attack to trigger Studied Combat . At which turn would it start? The first? The third? If it starts on the first turn you essentially wasted 3 rounds of Studied Combat.
- Thematically different:
The studying for Death Attack is about stalking your target, not attacking it until the time is ripe (You use standard actions rather than move actions to study the target). For Studied Combat the studying is about stopping for a second to size up your target and then attacking with a plan (You use your move action rather than your standard action).
2) There is no method to convert Studied Strike to Sneak Attack, and most likely there never will be. During playtest the investigator class had Sneak Attack. However, it was deemed to take too much away from the rogue and thus was changed.
This is an argument both for and against letting you change it, should you ask your GM.