Does Deathgrip need to successfully kill a unit (have it go to trash) in order to give the might bonus, or does the bonus still apply if the kill is replaced by an effect like Soraka's ability?

Ruling: Deathgrip does not require the unit to actually die or go to trash to give the might bonus. You must execute the kill instruction, but if it gets replaced by a replacement effect (like Soraka or Sett Legend), you still get the might bonus as long as the target remains on the board.

Nuances:

• If the kill target is removed from the board by another effect before resolution, Deathgrip won't be able to find the unit to reference its might, so you only draw 1 without the might bonus
• This differs from Baited Hook, which specifically references the "killed unit" (a status that only applies when a unit moves from board to trash)
• Soraka cannot save a unit that is larger than her current might when Deathgrip is cast, because the kill instruction happens before she would receive the might bonus from that same spell