Can Udyr use his activated ability (which requires spending a buff on him) to buff Wildclaw Shaman after Lee Sin buffs Udyr, or does the buff get consumed by Wildclaw Shaman's play effect first?

Ruling: Udyr cannot use his ability between playing Wildclaw Shaman and Wildclaw Shaman's effect resolving because Udyr's ability is at base speed. Udyr must consume a buff on his own card ("spend my buff") to activate his ability.

Sequence:

• If you use Udyr's ability before playing Wildclaw Shaman, the buff won't be there for Shaman to spend
• If you play Wildclaw Shaman first, you cannot activate Udyr's ability in-between because it's base speed, so the buff will be spent by Shaman's effect

Nuances:

• The colon (:) in Udyr's ability text denotes a cost:ability relationship, meaning spending the buff is the cost to activate the ability
• Udyr's ability is an activated ability, not a triggered ability that automatically happens when you spend his buff