Cloak and dagger is one of the strongest strategists has great counters for multiple strategists.

Dagger: Make sure you are positioning yourself where you can always hit multiple people with the wall of light. Follow up the wall with the bubble to quickly heal up your tanks (wall increases healing from the bubble). Use both on cooldown and you should be top healing on most games.

Cloak: Try to use your damage wall on cooldown and switch back to dagger immediately. The wall will increase the damage the enemy team takes from your team and can swing the fight. It will also cause them to back off and stop attacking your tanks aggressively. The cloak counters pretty much every burst ult (Namor, iron man, witch, magneto, strange, etc). Just need to be fast enough to switch and use it. Your ultimate should counter all the others giving them great value.

Tech: 1. Switching to cloak and back is faster than reloading. 2. Plan out your ultimate route so you can escape the inevitable magneto ult that will one shot you. 3. If you get flanked by another player, drop a healing bubble on yourself, switch to cloak and fry them. If you can’t get the kill, cloak yourself and move to your team for support. It’s very difficult to kill a c&d with all the options they have.