Concentration Domain

When you choose this domain at 1st level, you gain proficiency with Martial Weapons

Starting at 1st level, your concentration spells are more effective. Whenever you use a spell that needs concentration on yourself, choose an ally to also gain the benefit of that spell while you maintain your concentration. This increase to 2 allies at the 9th level and 3 at the 18th level

Disciple of Concentration

Also when you take this subclass you learn the following Domain spells at the corresponding level.

First level: Heroism, Find Familiar and True Strike
Third level: Invisibility, Enlarge/Reduce
Fifth level: Counterspell, Haste
Eighth level: Polymorph, Freedom of movement
Eleventh level: Anti-life shell, Fly

Channel Divinity: Blessing

As an action, you can bless a number of allies up to your wisdom modifier (Minimum of 1) within 30ft of you. For the next minute those allies can choose to gain a +2 bonus to their attack, damage, or AC for the duration.

Blessed Concentrater

Beginning at 6th level, when you have targeted yourself with a concentration spell a number of your allies up to you wisdom modifier (minimum 1) gain temporary HP equal to your wisdom modifier (minimum 1) per round. These vanish once the spell's duration has ended.

Divine Strike

At 8th level, you gain the ability to infuse your weapon strikes with divine energy. Once on each of your turns when you hit a creature with a weapon attack, you can cause the attack to deal an extra 1d8 radiant damage to the target. When you reach 14th level, the extra damage increases to 2d8.

Supreme Concentration

Starting at 17th level, when you cast a concentration spell on yourself a number of allies up to your wisdom modifier (minimum 1) gain a bonus to their saves for the duration equal to your wisdom modifier (minimum 1).