Do a beginner difficulty run. Its a cakewalk if you have completed insane difficulty. I kind of found enjoyment from one hit killing on less than 50% chance to hit after often missing with 87% chance to hit on insane and needing three more well placed shots too kill an underling. If any character is somehow allowed by yourself too take five direct hits then they usually only go into a down state from which they can be revived.
If you play missions offline but update your cloud save between them you can always delete your local save when offline to reload your last online save point. Did it legit myself but this would have taken a lotta stress outta the equation and was suggested by SaltyNasty.
It is insane how easy easy difficulty is... If you play it smart a single character could beat any mission but not boss on beginner. I recommend killing multiple units before ending the second mission after the tutorial. The two units you rescue do not gain experience but your two main characters do and you can accrue a tonne if you just sit near the exit too the mission and let enemy units parachute in every turn or soo.
Hiccups are boss fights. Moves are permanent obviously and for me it came down too a single pistol shot too take down the brumak. Next turn I would have been toast since two emergence holes had spewed units and missile reticules were all over my guys. Had to have gabe use his lvl 1 support ability too give old man vanguard character a single AP too possibly hit with his pistol since the boss had swung around to have his back unhitable by anyone else.
Having a scout speced for single running can take a bit, I wouldnt recommend solo running scavenger missions until you have at least extended cloak skill, (lvl 3 required to get) and at minimum a basic armor that give the skill potential (30% skill cooldown reduction) or at least armor that gives the skill blitz (if you didnt shoot 30% for extra AP). All weapon upgrades/leg armor that upgrade movement are beneficial. Near the conclusion of the game there was a scavenger mission that only gives you 2AP each turn and if I hadnt given them such great equipment for solo running they would have been toast.
Act 2 boss is the easiest one of the three, you can still plant a grenade even if youve thrown one recently, place them on top of emergence holes before they open and stay out of the red zones.
Final boss is the only true challenge on beginner and you should really think about each move you make. It certainly helps if youve beat the boss before, nearly necessary I'd say but if youve beat insane you should be aware of his routine. I did at one point have a 350 hp left sniper get hit by a direct rocket hit... stupidly thought I could destroy the rocket launcher while also having a little melee guy at my heels and having the crippled effect. They ended up surviving but just barely. Down too a true sliver of health like 10hp while in the downed state, I revived them next turn and did not take any risks after that.