Idea for New Spell (weak spell)

Name : weak spell
Training Cost : 20.000 Elixer
Target : Defend and Troops (clans castle)
Effect Type : Reduced damage 15 %(depending on level)
Damage Type : This spell has no damage just weak the damage of defend and troops
Training Time : 30 Minute
Description : use this spell to reduced damage
Research : Spell lvl 2( damage reduced 25 %; cost 25.000; training time 30 minute; upgrade time 12h)
Spell lvl 3( damage reduced 35 %; cost 30.000; training time 30 minute; upgrade time 1d)
Spell lvl 4( damage reduced 40 %; cost 35.000; training time 30 minute; upgrade time 3d)
Spell lvl 5( damage reduced 50 %; cost 40.000; training time 30 minute; upgrade time 5d)
Spell lvl 6( damage reduced 60 %; cost 50.000; training time 30 minute; upgrade time 7d)
Lab level : Spell lvl 2 ( Lab level 4)
Spell lvl 3 ( Lab level 5)
Spell lvl 4 ( Lab level 6)
Spell lvl 5 ( Lab level 7)
Spell lvl 6 ( Lab level 8)

Please comment and tell me what you think! Thanks for reading!