Question about the the actual effectiveness of Combat Casting giving Advantage on Concentration checks: Am I right that this will be a bigger advantage at lower rather than higher levels? My recollection of the Basic rules is that the DC for the check is half the damage you take or DC 10, whichever is bigger. As levels increase, so does the average damage you might take from a hit. I seem to recall that the 'effective bonus' you get from Advantage declines as you move away from the middle of the DC range (i.e., goes from +5 in the mid DC range down to something much smaller for a high DC).
That said, I don't really know what the damage scaling is across levels. So, it could be that you will only rarely be taking more than 20 pts of damage on a hit even at higher levels.
Just curious if anyone has done the math. If they designed the feat well, it would be a meaningful but not overwhelming advantage across levels for most casters-- while being a large advantage for those who wade into melee (which is dangerous enough for most casters even with advantage on concentration).
Either way, being only able to have one concentration spell at a time solves most of my buff spell problems from 3e. "Hey, we're going into a big combat. Let's spend the next hour distributing buff spells while the DM goes to sleep and prays that he has still designed an appropriate challenge for his PC's"
Whether it turns into a feat tax is another question entirely.
AD