Short of control decks, if you are playing with red cards, you are playing with max copies of Lightning Bolt
The mana cost is on the front side of transforming cards
Turn over turn, Weeping Angel will suffer from the drawback of the opponent being able to turn it off as a blocker by casting creature spells, but this wont always be an option, and through discard or counterspells, there are tools for Dimir decks to save Weeping Angel from opposing removal, all while being able to attack the opponent or their planeswalkers with a vigilant creature that is quite unpleasant to block
The fact that it kills basically everything, including Tarmogoyf, is a huge bonus
You may cast that card without paying its mana cost if the resulting spell's mana value is less than or equal to N
Cryptolith Fragment is another solid way to generate life loss all over the place