damage% modifiers can exceed 100% as long as you have the same specified effects as for demi-humans like on FBH. its just not advisable to stick to modifying damage on one attribute(demi-human) only.
like for example, you have lets say 1000damage on Cecil Damon on lhz_dun03.
with 2fbh cards, you'll deal 2000 damage, put 4goldenrings and you'll deal 3000 damage.
but if you put on 2fbh cards(that's x2, so 2000damage), then put 4mandragora cards(that's 20%more damage to wind property targets since Cecil is wind) you'll deal 3600damage(better than having 2fbh+4goldenrings)
damage calculation is 100% x (race modifier, like goldenring for demi+25% and caramel for insect+20%) x (element modifier, kaho for earth+20% or vadon for water+20%) x (size modifier, desert wolf for small, skelworker for medium, minorus for large all +15%)
while abyss knight is a special case of a boss or nonboss monsters, the paper for crit damage on any monster, and turtle general as universal