This weeks card of the week Dragon Mask forms a combo with Sneak Attack, Purphoros, Bronze-Blooded or similar effects.
Dragon Masks activated ability currently reads “Target creature you control gets +2/+2 until end of turn. Return it to its owner’s hand at the beginning of the next end step. (Return it only if it’s on the battlefield.)“.
Sneak Attack allows you to cheat a creature from your hand into play with haste for a single red mana, the downside to this is that the creature is sacrificed at the end of turn. Dragon Mask not only provides a +2/+2 buff to the creature but also returns it to hand at the beginning of the next End Step. Allowing you to play Drakuseth, Ilharg, or Dragon mage repeatedly.
As both Dragon Mask and Sneak Attack’s triggers will happen at the begging of the next end step you can stack the triggers to return the creature to hand as opposed to sacrificing it.
It also combos well with decks that steal your opponents creatures, cast Act of Treason on your opponents commander or threat, pump it up swing it back at them and then return it to their hand at the end of turn.