Backup allows you to put a +1/+1 counter on a creature on ETB (enter the battlefield for the uninitiated), and if you choose another creature it gets an additional ability until the end of the turn
Its a huge 8/8 trampler that must be dealt with, but at the same time, your opponents wont be too keen on doing it, fearing what the dead monstrosity can reanimate to the battlefield
If you can cast a spell with delve from your graveyard using flashback like the ability from Snapcaster Mage, you can apply all the rules from the mechanic
ninjutsu A keyword ability that lets a creature suddenly enter combat
Using Golos, players built Ramp decks that sought to play this pilgrim as early as possible in order to fetch a Field of the Dead from their deck
For example, Firebending adds red mana to a player's mana pool during combat, and Earthbending turns lands into creatures