BASIC GAMEPLAN
Korg, Scorpion, Ice-man at Location 1
Cosmo at Location 2
Sandman at Location 1
Ronan at Location 2
Taskmaster or Mystique+Card draw at Location 3
CARDS
Ice-man: Slows down the hand. Ice-man should be played after Korg if you start with both.
Scorpion: Afflics cards with -1, discouraging the opponent from playing those cards. Very effective when played after Baron Mordo and/or Maximus. Reduces Rocks to -1 power.
Korg+Rockslide: Add Rocks to the deck, locations and other effects may otherwise draw out the deck. These cards should be played as soon as possible to increase the chances of bricking your opponent's draws. Good against Lockjaw, Thor, and Jubilee.
Baron Mordo+Maximus: Card draw. Baron Mordo's disruption is minimal and is played because of his niche of drawing your opponent a card. These cards can be played on the final turn so your opponent cannot benefit from the drawn card(s) or before then if it can fill up your opponent's hand, denying them their next draw. You can tap on a player's portrait to view advanced details. The hand-size limit in the game is 7. Take into consideration how many cards your opponent may be able to play if you do not have Sandman.
Cosmo: Stops Enchantress and Shang-chi from destroying Ronan. Stops your own Taskmaster, Mystique, and card draw effects from being activated so be careful.
Sandman: Lockdown. Sandman stops you from playing Mystique+card draw on the final turn, so plan ahead. Very important to have alongside Ronan so the opponent cannot dump all the rocks on the final turn, weakening Ronan significantly. Turn 4 follow-up to a turn 3 Maximus makes can make it much safer.
Ronan the Accuser: The centerpiece of the deck. It is important to get Ronan on board, otherwise Taskmaster and Mystique have no targets. Weak to Shang-Chi, Enchantress, and Rogue. The first will not stop Taskmaster or Mystique from copying Ronan's power/ability, but the latter two will result in a 3-power Taskmaster and a blank Mystique.
Mystique: Used on the final turn (after Ronan) with Mordo or Maximus. If she and Taskmaster are your final-turn options, play Taskmaster unless you can draw your opponent cards.
Taskmaster: Copy Ronan's power, or Maximus if you're desperate. Check notes for maths for him and Mystique copying Ronan. TL;DR if you don't have Sandman, don't play Taskmaster; always play Taskmaster instead of Mystique unless you have card draw effects.
Dr. Doom: A 15-power push that can reach into Sanctum and Flooded locations but requires open spaces for maximum efficiency. Sometimes the better turn 6 play if your opponent doesn't have a lot of cards in hand and you cannot make them draw. Works well with Sandman.
SUGGESTED CARDS
America Chavez: Can help with deck consistency. It is important to find Sandman and Ronan as soon as possible: Sandman to stop hand-dumping, Ronan because 2 cards are essential dead without him (Mystique and Taskmaster).
Arnim Zola: Zola can be used to duplicate Ronan to two other lanes; Macimus to draw more cards; or Taskmaster and Mystique to re-activate their copy abilities.
Leader: Ronan can easily hold a lane by himself and an aggressive start can quickly put you ahead, with Sandman making it difficult to close the gap. Leader is used to help secure the match, but be aware that some card abilities can destroy your board.
Psylocke: Primarily used turn 2 to play Sandman or turn 3 to play Ronan. It is important to get these cards out quickly, especially Sandman. If you play Ronan on turn 4 then you should follow up with Taskmaster or Mystique+Baron Mordo on turn 5.
MATHS (Assuming 4 cards in hand, opponents plays 0-2 cards)
Taskmaster on 11-power Ronan: End with 11-power Ronan, 11-power Taskmaster = Total 22 power. May drop to 18 or 16 power, would suggest not using Taskmaster if you do not have Sandman.
Mystique on 11-power Ronan: End with 11-power Ronan, 8-power Mystique = Total 19 power. May drop to 15 or 11 power.
Mystique+Mordo on 11-power Ronan: End with 13-power Ronan, 10-power Mystique, 3-power Mordo = Total 26 power. May drop to 22 or 18 power.
Mystique+Maximus on 11-power Ronan: End with 15-power Ronan, 12-power Mystique, 7-power Maximus = Total 34 power. May drop to 30 or 26 power.