Horde Survival Arena + Deckbuilder, can that work? I think so, and i think this Game proves it.
Customize the Card Pool you get to build your Deck with and survive Hordes of Aliens, even stranger than you.

One Possible Combo, might look like this: 

Progression

• Unlock new Cards to Customize your Run-Deck

• Unlock new personalities, drasticly changing how to best build during the next Run

• Unlock even Higher Difficulties with more Aliens, more Rounds, more fun and more randomization (Bigger Cardpools)

In a Run

You will

• Enjoy Short, action-packed Waves of 15-120 Seconds

• Level Up and Choose where to take your Basic Character stats from a Random Choice of 3 randomly Chosen Upgrades

• Buy Cards from the Shop between Rounds 

• Start of struggling for Survival

• Become unstoppable or die trying

In a Round

You will

• Earn Xp and a Strange form of Currency by Destroying as Many Aliens as Possible

• Either Try to Survive, or go on a killing Spree

• Use your activatable Cards to either:

• Permanently Scale your Characters Power

• Temporarily Get Big Powerboosts and Combos

• Or Unleash Devastating Special Attacks

Between Runs

You can

• unlock new Difficulties, Characters and Cards

• Customize the Pool of Cards the Shop can hold for you in the next run

• Check out your previous Runs and Compare your performance with your Friends

Proudly Powered by Godot Game Engine. 

Made in Germany