mtg blue discard cards Rules Text: Discard, Colors: Blue, Black, 914 Magic the Gathering Adventures: Shadows

Some creatures like Agent of Treachery are bad enough when you get hit by their ETB once, but you can easily use them again and again while also jumping ahead on lands to drop other powerful cards

Light-Paws offers the gift of flickering, allowing you to momentarily exile a creature only to have it return, retriggering all its delicious enter-the-battlefield effects

It has Vigilance and Trample, and other dinosaurs you control get +1/+1 as well as Vigilance and Trample

Espers to Magicite exiles all enemy graveyards and lets you copy one of the creatures within them

While it requires you to track and remember specific things each turn in order to resolve the trigger in the end step, it does remove the need to disrupt the middle of someones turn to announce triggers in the manner required by cards such as Rhystic Study or Smothering Tithe