Escalation Monster

The Escalation Monster is a type of monster that stores in the Extra Deck. The border of that card is half black and half white, similar to that of Pendulum Monsters. They also possess a special Cost Energy, which is an indicator which is specifically designed for them.

How to Summon it
First things first, check out your Extra Deck for a monster that can be Summoned. If your LP are exactly equal to the value in that card's Cost Energy, you can take 1 monster you control and send it to the Graveyard (taking into account that this follows any special requirements the Summoned Escalation Monster follows), and if you do, Special Summon that monster from your Extra Deck. That is an Escalation Summon.

What are Cost Energies?
The Cost Energy is an indicator that applies only in Escalation Monsters. They are shown in the right side of the card, next to the artwork (here that the black side of the card's border is replaced with white), and the value is written vertically, in a a greyish box, using green font color. That value is the amount of LP you have to have (exactly) to Escalation Summon a monster.