Powers that let you shift (or pull/push/slide/whatever) sometimes seem vague on whether you have to shift/other the full distance, or if you can only shift part of it (shift 3, when powers states shift 5). The feat in question here is Driving Rain (see below).

Do I have to shift all the way to the target? Can i choose not to shift at all? Could i shift partway?

Also, rules about this in general would be appreciated. To be more specific, here i mean rules for powers that let you move (shift, fly, teleport, etc.) and powers for forced movement; about how far you can/have to pull/push/shift.

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Driving Rain

Paragon Tier
Prerequisite: 11th level, monk
Benefit: You gain a feat bonus to bull rush attack rolls equal to your ki focus’s enhancement bonus. When you hit with a bull rush, you push the target a number of squares equal to your speed, then shift into any unoccupied square adjacent to the target at the end of the push.

Published in Psionic Power, page(s) 137.

 

Hmm, could i choose not to shift at all with Driving Rain, but still push them?

As Mand 12 you are not necessarly required to Push it and you could Push it all, some or none of the squares mentioned. Additionally, since the Shift has a destination, you'd have to decide if you Shift to a square adjacent to the enemy or not Shift at all.  You couldn't Shift partway.

Here is the revelant Rule:

PHB 3 Glossary Move: If a power notes a distance that you or an ally moves willingly (for example: "you shift 2 squares"), the character allowed to move can decide to move all, some, or none of that distance. Similarly, if a power forcibly move an enemy (for example, you push the target 3 squares), you can decide to move the enemy all, some or none of that distance. If a power notes the destination for your or an ally's move (for example, a square adjacent to the target), the character allowed to move decides either to move to that destination or not. You can't move partway. Similarly,  if a power specifies where you force an enemy to move, you decide either to move the enemy there or not. 

The way you move to your destination in this fashion, the Rules don't tell. Some powers state a number of squares that the pursuer moves but this one does not. RAW You could Shift all over the Battlefield as long as you end up adjacent to the enemy it'd be okay techically.

For sake of simplicity and consistency, I would assume that every squares need to take you closer to your destination.