Blood Artist targets a single opponent, whereas Vindictive Vampire hits all opponents and does not target (in case hexproof is relevant). The cost doesn't matter as the intent is not to cast this from hand at all.
Hey, I just wanted to extend my thanks to both snowfox54119 and Zervintz for your contributions to this topic and actively pursuing upgrades and enhancements to this incredibly fun and dynamic commander.
I got into EDH about 2 years ago with some precons, but the first standalone commander I started brewing was Grenzo, Dungeon Warden off of a super budget EDH deck list that I ordered for $31.51 USD.
Contributors and guides like yourselves are an incredible resource to the mtg community and you should know that it has been highly appreciated.