Ok, let's split it into two questions: How to fight ninjas, how to win Big Enchilada (you talk about 3* cover)
How to fight ninjas: you have several types (I don't remember names)
- the weakest: They turn into smoke = attack tiles when they die
- the normal: normal ninja occasional shuriken, etc.
- the boss ninja: has meteor hammer
First of all, you can tell which countdown tiles belong to which enemy.
When you cycle the enemies, their tile will pop up for a sec.
So I usually leave the weakest ninjas until the end because if it's one wave fight, their attack tiles don't matter.
Also you can usually kill them with one spell (even AoE - spell that hits multiple enemies)
One thing to note is that if they are stunned when they die, they don't turn to smoke.
Normal ninjas I attack regularly, just dealing with their countdown tiles.
Boss ninjas are low priority because the meteor hammer has big countdown which you can usually prevent (stunning, matching).
Now how to win big Enchilada
My go to team with only 2* characters is thormneto - Thor, Storm, Magneto.
There are 4 waves, 1st and 3rd are henchman, 2nd and 4th are heroes.
During first wave you try to have as many colors as possible without getting injured too much (small injury is fine)
You need to prioritize blue and purple, because storm's blue is crucial during wave two and magneto's purple makes more blue matches.
Ideally if you have 22 blue by the end of first round, you are good to go.
Just be sure, you use spell to finish off the last enemy, because it will be still your turn, when the heroes arrive (and they might not even pop spells)
I usually use magneto red to finish off the enemy, because it deals about 2 dmg and provides you with extra colors the explosion destroys.
In the hero round you just stun 2 enemies with storm blue which deals massive aoe and then kill the remaning hero.
Also extra help is Thor's yellow usually creates green cascades and you are better off using Storm's green, because it clears the board and destroyed tiles count in your total (so you can pop more magneto purple, or storm blue)
Rinse and repeat for rounds 3 and 4.
Anyone please help with formatting. I can do only in few hours time.