Static Charge's ability grants an ability to the creature to which it is attached. This results in the creature being the source of the damage, not Static Charge.
For example, if Static Charge is attached to Shoulder Id, Static Charge's ability grants a new ability to Shoulder Id, meaning Shoulder Id's text box now reads (numbers for reference):
Taunt.
Shoulder Id cannot fight.
When Shoulder Id would deal damage, steal 1 Æmber instead.
At the start of your turn, deal 2 damage to each of this creature's neighbors.
At the start of the Shoulder Id's controller's turn, Ability 4 resolves and Shoulder Id would deal 2 damage to each of the creature's neighbors. However, since Shoulder Id would deal damage, that dealing of damage is replaced with a steal via Ability 3, and Shoulder Id's controller steals 1 Æmber. Since all damage is dealt simultaneously, the dealing of the damage only happens once, which means the replacement of that damage will also only happen once, resulting in Shoulder Id stealing 1 Æmber.
to each of this creature's neighbors."
For example, if Static Charge is attached to Shoulder Id, Static Charge's ability grants a new ability to Shoulder Id, meaning Shoulder Id's text box now reads (numbers for reference):
- Taunt.
- Shoulder Id cannot fight.
- When Shoulder Id would deal damage, steal 1 Æmber instead.
- At the start of your turn, deal 2 damage to each of this creature's neighbors.
At the start of the Shoulder Id's controller's turn, Ability 4 resolves and Shoulder Id would deal 2 damage to each of the creature's neighbors. However, since Shoulder Id would deal damage, that dealing of damage is replaced with a steal via Ability 3, and Shoulder Id's controller steals 1 Æmber. Since all damage is dealt simultaneously, the dealing of the damage only happens once, which means the replacement of that damage will also only happen once, resulting in Shoulder Id stealing 1 Æmber.