To spend ink when playing cards or activating abilities, exert the number of cards equal to the ink cost (by turning them 90 degrees sideways)
Paying a single green mana to dump your entire deck into your graveyard (assuming you dont run basics) enables a bunch of busted combos
If a creature enchanted with an Aura that has umbra armor would be destroyed by multiple state-based actions at the same time (most likely because a creature with deathtouch has dealt damage to that creature greater than or equal to its toughness), umbra armor's effect will replace all of them and save the creature
But if you get more than one Warlock Class to level 3, their level 3 triggered abilities will each trigger at the beginning of your end step, and if the first one to resolve causes an opponent to lose life, that life loss will be counted by the next one to resolve
7.8/10$0.27 Susurian Voidborn Creature Vampire Soldier 2/2 Whenever this creature or another creature or artifact you control dies, target opponent loses 1 life and you gain 1 life
A cheaper but a bit less good Chaos Warp