Paying three black to draw 7 and then an additional black to get those 7 cards will cost a lot of life, but it seems like in most scenarios you will get pretty insurmountable card advantage out of that, and 7 life will be worth it
Meteor Blast Not great, but if you really need a lot of targets, perhaps because youre playing Hinata, Dawn-Crowned, Meteor Blast can do the job
Youll see later which cards those were, if you cant already guess
These four are very powerful, but their value is totally related to how fast you can get experience counters
Tithe (T1, Ext, S, Block) A mini-Land Tax with one advantage: it can grab the original dual lands