Let’s start by saying that in this case i’m the Thresh, I first picked him as I think Thresh is versatile and has no counters. I believe the only counter to Thresh is being bad at him or playing him when you are not focused.
Thresh’s strengths
Thresh allows for versatility both as an aggressive “trade-focused” support, but at the same time he can be played passively as each spell can be used for peel.
Graves’ Strengths
Graves is extremely strong due to the fact that he has a pretty high damage but the big thing for him is how fast he can dish it out.
Graves biggest strength lies in the fact that as long as he is positioning well, after the support gives him a good chance to be aggressive, he has the opportunity to do his combo, while avoiding most of the opponents damage.
Duo Synergies Thresh/Graves
The Thresh/Graves duo is in my opinion comparable to Annie/Graves and Leona/Graves.
Once the Thresh does a good play, the Graves will dish out his combo and then dominate the lane.
The differences between the other 2 bursty supports stands in the multiversatility of Thresh.
Thresh can be played also passively and doesn’t need to risk killing himself to make a play.
On the other hand the Annie/Graves combo provides little to no variations in the style of play, while the Leona might find herself into extremely frustrating counter matchups.
Morgana’s Strengths
Morgana is a great champion overall, she has the black shield which basically counters all cc’s and has a good amount of damage output, even with little gold.
While in a solo lane a Morgana is pretty much unkillable, when she is chosen as a support her style of play can determine whether she can be killed or not.
I believe Morgana to be extremely solid, as long as played reasonably and while keeping a big eye on not overextending
Jinx’s Strengths
Jinx is in my opinion one of the strongest if not the strongest adc at the moment.
The reason being that she has high damage and a decent level of self peel.
If paired with a defensive support she is allowed to shine from level one with the ability of poking with her high range rockets, while having the chance of punishing miss-calculated all ins with her chompers.
Duo Sinergies Morgana/Jinx
Morgana/Jinx strucks me as a unidimensional lane in which they can either snowball their advantage or fall behind and wait for the Jinx to have a couple items and the Morgana to have her zhonyas.
The Matchup Thresh/Graves vs Morgana/Jinx
Thresh/Graves vs Morgana/Jinx is going to be pretty much decided by their level 1 and the respective supports to land their Q.
As Morgana has the black shield on her side, I do give her the edge in terms of play making.
Yet most Morganas don’t max that as they tend to focus more on maxing the Q for lowered cooldown and increased damage.
This leaves a big opening for the Thresh to have his Q cooldown being lower than that of Morgana’s black shield.
Therefore the lane can be decided by the ability of the Thresh to land a couple hooks in a row.
Being the Graves so bursty, while Jinx is more pokey, allows the Graves/Thresh combo to win if they can get a couple of good engages in a row.
In my opinion this lane is to be won by the Graves/Thresh, while the Morgana/Jinx should either auto win it or have a cs advantage.
What can go right and what can go wrong
Level 1 should be won by the Morgana/Jinx, they have so much poke ability and the dominance of spellthief is going to shine the most here.
Level 3 is when the lane can be contested, having the Thresh with all his skills, this is when the Thresh/Graves has to do something in order for them to turn the tables and start dominating the lane.
If they were to succeed they would have the Jinx having to farm with rockets or by being extremely cautious. When that happens it will leave even more room for the Thresh to be aggressive.
Level 6 might go either way but will be in favor of who hit it first.
I believe that if Graves/Thresh reach level 6 first, there is no way that the Morgana/Jinx can win the all in.
The reason being that Graves ult is instantly castable, while Jinx’s ult will require some time.
Also as the Thresh player I have found myself having to just place myself in front of Jinx to avoid her hitting the ult on the Graves.
Conclusion and how it goes in my experience
In my experience the Thresh vs Morgana matchup is always hard.
A good Morgana will know that she has 75 range over my autoattacks and will keep being aggressive.
Landing one bind can literally mean the end of the matchup as Jinx will have the chance of following up with her chompers.
Same goes for a good jinx, using rockets to constantly pressure the Graves, starting from level 1.
They won’t necessarily grab level 2 first although I believe that if they were to achieve that, the Morgana should be flashing onto the Graves to either force his flash or get him to die.
As I said I don’t think there’s high synergy between Morgana and Jinx and that’s because if they were to play super-aggressive, which is what they tend to do in my experience, they would find themselves being overextended and easily gankable.
As always skill can change the results, yet as a general conclusion I believe that the Morgana/Jinx combo has to win early in order to maintain their supremacy.
If they were to just let the Graves farm, at level 6, they will get destroyed.