Archer's bow

You use an action to use the spellslot of 1 or higher and activate the bow and when you do you can use its attack directly.
The bow stays active for 1 minute before it deactivates again.

While the bow is active you can use your attack action to fire a luminous arrow that targets one creature within 60 feet of you. These arrows deal (1d8 + wis modifier) radient damage.

You can shoot 1 additional arrow per attack at level 5, 11 and 17 in order to shoot these additional arrows you must use a higher lvl spellslot when activating the bow:

 
While both the Archer's bow and Starry form are active you gain the following bonus:

Archer
After using the attack action with the Archer's bow you can make a ranged spell attack as a free action, firing 1 extra luminous arrow that targets one creature within 60 feet of you.
On a hit, the attack deals (1d4 + wis modifier) radiant damage.

Chalice
You can choose to make your luminous arrows heal on hit instead healing for ((druid level +  wis modifier) / 3) rounded down per arrow.

Dragon
When you make an Intelligence or a Wisdom check or a Constitution saving throw to maintain concentration on a spell you can roll with advantage.
(You can use the dragon bonus even when the bow is not active)

This bow can be used as your spellcasting focus.