Dwarf clerics mend is to strong on mega buildings

[Kronox]

The dwarf mega builings are on their own quite hard to deal with. They howver become basicly near indestructible/ have to be killed in one turn because of the dwarf cleric. The mend ability heals up to 1600 hp ( seems to be 20 % of the base hp) without any research or what so ever to an mega building so only 5 clerics around are enough to heal an dwarf mega building to full health in one turn.

As an possible fix I would suggest to give the mend ability fixed values with perhaps ,,effectiveness,, against certain types instead of an percentage heal.

As an example

40 hp base,
And
+ 50 % for buildings (+ 60 hp)
+ 100 % for fortified buildings (+80 hp)
+ 750% for mega buildings ( +340 hp)

Mechanical ( +40hp).

This would be still better than repairing stuff with workers but the mend for mega buildings wouldn't escalate that easily.