have u read jugo taka's skills? HERE:

his 2nd passive will resurrect the defeated ninjas (aka gaara in your case) when using the mystery while his life higher than 30%, so i assume when u used his heal mystery he already had 30%+ hp.

+for the minato frags u get them from events, mostly exchanged/redeemed by points, u can get a limited amount of them tho but c*so spend coupons for more