Board Thread:Questions and Answers/@comment-5551215-20160530174617/@comment-26140304-20160531030856

Indeed, Kulyuk is the best Spark Fire-unit buffer in the game, but he's really only used for one quest, so it's only short-lasting. Alternatively, you can use either Seria or Adel as your Spark buffer instead.

As for Trials, you're most likely going to be using either Eze or Vern as your Spark buffer, both of which carry higher Spark buffs than Kulyuk. Since you have two Kulyuks, you might be best going with these two setups: Option 1 involves a tanky BB utility setup and Option 2 utilizes healing.
 * SP Option 1
 * Boosts Atk relative to remaining HP (10)
 * Enhances BB gauge fill rate boost effect added to BB/SBB (10)
 * Adds enormous Def boost for 3 turns effect to BB/SBB (20)
 * Adds BB gauge boost when attacked for 3 turns effect to BB/SBB (50)
 * Enhances BB gauge boost when attacked for 3 turns effect (10)
 * SP Option 2
 * Adds BB gauge boost when attacked for 3 turns effect to BB/SBB (50)
 * Enhances BB gauge boost when attacked for 3 turns effect (10)
 * Adds HP restoration when damage dealt effect to BB/SBB (40)