For ruin domain:
bonus spells:
1st earth tremor, thunderwave
2nd dust devil, shatter
3rd erupting earth, wall of sand
4th conjure minor elementals, hallucinatory terrain
5th animate objects, transmute rock
Bonus Proficiency
When you choose this domain at 1st level, you gain proficiency with heavy armor.
Channel Divinity: Siege Monster
Starting at 2nd level, any attack or spell you use does double damage to objects or constructs.
Channel Divinity: Spirit of Desolation
Starting at 6th level, you can use your action to cause a damaged object or construct you can see to have an aura of desolation for 1 minute. All creatures who touch the object during this period will take 2d8 psychic damage.
Divine Strike
At 8th level, you get 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 thunder damage to the target. When you reach the 14th level, the damage increases to 2d8.
Haunted Ruin
Starting at 17th level, you can cast the antipathy spell on an object that has been damaged. You need to complete a long rest before you can use this ability again.
This is sort of a hybrid of a cleric who wants to spread ruin (thus siege monster and divine strike) and one who wants to guard a ruin (thus hallucinatory terrain and haunted ruin), or maybe just one who created a ruin while younger and now guards his handiwork. Regardless there is probably a lot of dust and rubble lying around, which makes dust devil and wall of sand seem appropriate.