pretty good deck for getting hela + colleen early on in pool 3, building off of typical hela-only decks but removing a cable for colleen iirc. i've had a lot of success at collection level in the 600s.
suggestions are almost all pool 3 cards i don't have but which could potentially be useful. i think dracula and ghost rider in particular would work well, and gambit has screwed me over when opponents have used it, while moon knight is solid disruption. hell cow might be too much discarding though, since you always want to be wary of discarding hela.. it might work better in a more apocalypse-centered deck.
"helicarrier" seems like it'd be excellent since it's high power, easy to discard, and provides more cards which you could discard as well, and might help with a hell cow inclusion.
agent coulson is worth considering since the cards he adds to your hand are powerful and you get two of them, which can help with turn 4 if you're discarding but trying to avoid hela (of course, this won't save hela if your remaining discard card is lady sif). he could maybe replace white queen, though honestly i think the information white queen provides about the opponent in terms of what their hand is looking like ends up vital, and being able to use an opponent's 6-cost card finisher when your hand is mostly discarded and you haven't drawn hela can be a gamewinner since your early discard cards (blade, colleen, sword master) are good stats for the cost, leaving you ahead early on.
also invisible woman is probably very good since you can hide discards more easily and make sure they don't target hela, though i'm not sure what you'd cut for it-agent 13, maybe?
i don't have swarm included in this desk since it adds small things in your hand to discard, which i don't think you actually want.. morbius doesn't seem that powerful either, but i haven't tested him much-you definitely need to make sure the early game is either all discarding or adding cards to your hand, and morbius does neither.
as a note the only card in here that's not discard, add card, or big card: jubilee not only drags out a card from your deck that's usually high cost, but also manages to thin your deck, increasing the chance you draw the ever-so-important hela in the late game. usually if i have hela in hand, i'd rather play white queen, but if i don't yet, i play jubilee so that even if jubilee doesn't pull hela, it might cause a turn 5 or turn 6 hela draw to be more likely.
also keep in mind that a lot of the larger cards are interchangeable. i think you could definitely replace blue marvel and odin with other cards with powerful effects, since odin rarely manages to combo with the rest of the deck (though it's a power play when it does) and blue marvel doesn't usually end up with that many targets (but makes for a solid and consistent turn 5 play). i'd definitely consider magneto, leader, and giganto, though i can't say for sure if they're actually any better than what's here, and probably less consistent in terms of results.