There are a treasure trove of artifacts that cost zero or one mana, from Ornithopter to Chromatic Sphere, that can turn this into a broken card draw engine
On top of that, it reads: At the beginning of your next main phase, add an amount of colourless mana equal to that spells mana value." Basically, not only do you get to say no to something, you also get to cast something bigger on your next turn
If you arent aware, you completely exile an opponents library with Helm of Obedience and any one of those, which is certainly potent
This cost reduction even gets around Commander Tax, so if you need to recast her you can just gain some life and cast her again
Upgrades Swap out some of your lower-cost characters to ones with higher willpower to get the best use out of your healing abilities