Wolfir Silverheart is just what you need. He is probably better for your deck than Gisela. He can make any of your creatures hit like a truck

I have 4 copies of him in my binder...maybe replace an Angelic Destiny , 1 Gisela, Blade of Goldnight and the 2 Vorapede s for him?

The reason I want to keep Gisela is because she really helps me control combat

Have you tried Somberwald Sage for the more specific mana greedy creatures?

What do you side board in and out when facing decks like delver, or rdw?

Against delver, I usually go with sideboarding in 3 card:Autumn's Veil and 2 Corrosive Gale

RDW or Wolf Run Ramp/Aggro I add Celestial Purge and Beast Within ,

Delver: -1 Wurmcoil Engine , -2 Vorapede , -1 Wolfir Silverheart , -1 Angelic Destiny

+3 card:Autumn's Veil, +2 Corrosive Gale

RDW, WRR: -2 Vorapede , -1 Wurmcoil Engine , -2 Angelic Destiny

+3 Celestial Purge , +2 Beast Within

First game I basically ramp to big creatures to scare them, Generally, in the 2nd game, I take most of them out for answers let them think the ramp is for big creatures when its my smaller ones doing the damage. Plus, Delver and RDW play fast, so removing big creatures helps me keep pace with them without sacrificing too much of my deck.