Voice of Authority abuses? (Order Cleric ability)

[Merudo]

Voice of Authority: When the Order Cleric casts a non-cantrip spell that targets an ally, the ally can use its reaction to make one weapon attack against an enemy that the Cleric can see.

If more than one ally is targeted, the Cleric choose which ally can make the attack.

I've been wondering how to best exploit this ability to the fullest extend. So far I've discovered a few tricks that I'm going to share here:

• Friendly fire: the Cleric can include an ally among the targets of an harmful spell to let said ally have an extra attack. Best used if said ally is resistant/immune to said attack.
  
• Remote support: The Cleric can combine the Scrying & the Sending spell to give extra attacks to anyone in the multiverse.
  
• Multiclass: the "Voice of Authority" feature is obtained at level 1 and works with *any* spell, making the Order Cleric excellent for a one level dip for Wizards, Sorcerers, & Bards. Giving an extra attack on top of the other benefits of Haste/Greater Invisibility/Polymorph/etc is very nice.