Does the Navori battlefield buff stack each turn, or is it a one-time +1 buff that doesn't stack?

Ruling: The buff does not stack. A unit can only have one buff at a time (unless it's Green Lee Sin, who can have multiple buffs).

Sequence:

• Each turn you hold Navori with a unit, that unit would receive a +1/+1 buff
• However, the Buff mechanic prevents stacking - a unit can only have 1 buff at a time
• So a Might 1 unit after 3 turns of holding stays at Might 2, not Might 4

Nuances:

• Green Lee Sin is an exception and can receive multiple buffs from effects
• The italic reminder text about buffs not stacking doesn't apply to Lee Sin's specific ability