Does the Shield keyword stack when multiple units or effects grant Shield?

Ruling: Yes, each instance of Shield stacks. Multiple sources of Shield add together to create a cumulative Shield value.

Sequence:

• Each unit with Shield grants its Shield value
• Shield granted by other units' abilities adds to the total
• Shield granted by combat tricks (like Block) also adds to the total
• All Shield values sum together for the final Shield amount

Nuances:

• In the example with 2 Tarics and a Sunlit Guardian: one Taric would have Shield 5 (1 from itself, 1 from the other Taric, 3 from Block), the other Taric would have Shield 2, and the Guardian would have Shield 3
• The resulting might values would be: one Taric with 9M, one Taric with 6M, and Sunlit Guardian with 6M