Shovel Knight: Treasure Trove

Pretty easy to grind this one out on the first level, Plains, against the Black Knight.

You can theoretically get 12 deflection (reflection) shots against him if you only attack him with his blast. So you could get this with 3 plays of the level. Theoretically you could die right before you finish him off and just repeat to get the rest you need without playing the whole level as well.

First off, I suggest going into options and switching your relic activation to Button mode so that you only have to tap to use relics rather than having to use the left thumbstick/d-pad and button combo. It makes the entire game much easier IMO.

Head to the 2nd stage, Pridemoor Keep. Midway through the stage you'll reach a room with three enemies, two on the right and one on the left, firing red orbs into the center to a staircase-looking structure. Go ahead and climb to the top and reflect to shots back at the top-right enemy, then two more at the left-most enemy. The bottom right enemy can't be hit as the deflected shots hit the rock above him. Climb up the ladder at the top and hit the checkpoint. Then simply keep climbing down the ladder and reflecting two shots at the guy on the top-right. Each time you leave via the ladder and re-enter, he respawns, giving you two more opportunities for deflected shots. This can be done against the Black Knight in the Plains mission too, but that's much slower as you have to wait for him to jump around a lot between shots.

In the interest of creating as much of a one-stop-shop as possible, I've included 22 of the miscellaneous achievements in Shovel Knight in the video below. I wanted to include Knuckle Down as well, but the stage for that was already complete in my game and I haven't played back through again to unlock it. You can see this method for Reflect Lord at the 18:50 mark. I had already earned it so it doesn't unlock, but it shows the method I used.