When Heimerdinger copies tap abilities from friendly legends, units, and gear, does he copy all abilities simultaneously, and when activated, does he use only one ability or all of them at once?

Ruling: Heimerdinger copies ALL tap abilities from ALL friendly legends, units, and gear simultaneously. When you activate one of those copied abilities, you only activate that ONE specific ability, not all abilities at once.

Nuances:

• Heimerdinger copies the mana cost associated with the abilities (such as Viktor's pay 1 cost)
• Even though multiple abilities are copied, you can only activate one of them when you tap Heimerdinger