Ok, here is my advice, since I use a very similar strategy with Prof X:
First: Do NOT level Prof X any higher, you don’t want him to have the most powerful color on the team, since that will not benefit you from his Master Plan.
Second: Re-spec Black Widow Grey Suit to 5-3-5 and level her to 166. Her 
deceptive tactics is the BEST way to win with Prof X (IMO). Purple is her strongest color, and at level 166 will be higher than Prof X blue, so every match 5 will give you +4 
. When you use Deceptive tactics, you will be able to make 2 match 5’s EVERY TIME, sometimes 3, which will often let you do deceptive tactics AGAIN, right away, which then allows you to fire sniper rifle. Added to the 4k damage from Master Plan, even 20k hit point hulkbusters won’t last long.
Third: Match strategy—Boost +2 
/ 
AP; search for match 5’s above all else (obviously) then prioritize 
, and then 
. It takes 3 
matches to hit 11 
AP. Deceptive tactics into sniper rifle and game over!
There are a couple of drawbacks with this:
–High level boosted characters can have a stronger color than Black Widow’s purple, which will alter what you gain from Master Plan. Not a lot to overcome this, but hopefully whatever that color is has a strong attack. If it is green, it will feed your sniper rifle for over 4k AoE damage. If it is red, you can use the pistol to manipulate the board for more purple matches. Or it may feed a good attack for the boosted character. It also may be worth it to switch to Iron Fist for that event instead.
–Bad boards, with little purple or no purple matches. These happen, but thankfully not too often, and makes any match tough, regardless of who you are using.
I have been able to finish 4 matches in 9 minutes against max level 3/4* using this strategy, occasionally winning on my first turn with a couple lucky cascades (purple match 5 into another cascade is awesome!!)
Other than that, starting at 750 with 12-13 hours until the event ends, you can go 3-8-3 for shields (and avoid the heavy times at 11 hours, 8 hours and 3 hours before the end) trying to get 3 matches for 30+ points each hop (only 2 if the matches take too long), then try for 1 more high value match at the end if you need it! Don’t use the 24-hour shield that far out, if at all, since the 3-8-3 shield hops costs the same. If anything, the retals you can get from the hits will bring you higher than you started anyway!
I would say this works for me 3 out of every 4 events right now, although you do need to be diligent with skipping fights to find high-value targets.