Credence, Concentration and Caster Choices

So my elven ranger/sorcerer/monk who is currently composed of butterflies is currently invading the Spire at the heart of the Outlands to battle an immortal agent of cosmic equilibrium bent on genocide of her own apparently-mythical race.

What this means is I'm probably going to hit 11th level soon, which means a new Spell Known. Hoorah! I'm really indecisive about this sort of thing so I decided to brush up in advance and get some idea what I might want to learn. And I hit some snags.

Concentration Mechanics

See, 5e has introduced the Concentration mechanic. I actually really like this. I think it does a very solid job of nerfing the once-incontestable power of high-level casters who were able to stack up continuing effects like cordwood, either buffing themselves into superhumanity or dominating combats. You can no longer give yourselves several stat boosts, super-speed, flight, invisibility and immunity to elemental energy while also holding six orcs paralysed and trapping the rest under a cloud of toxic gas.

Where I run into a problem here is that Charlie is, amongst other things, a ranger. As a ranger, he's heavily reliant on hunter's mark to maintain a reasonable damage output. And hunter's mark requires Concentration.

As a preposterous multiclass character, Charlie is particularly reliant on hunter's mark to remain within playability tolerance, since I don't want to actively hinder my friends. How do we do that, then?

Charlie currently has hunter's mark and Colossus Slayer, plus a monk's Flurry of Blows ability. This means he gets 2-3 attacks per Attack action, and gets bonus damage on those. In a great round, he's dealing 1d8+4d6+2d4+16 damage given one attack with a +1 spear and two unarmed strikes. It's usually more like 1d8+3d6+1d4+11, or about 27.

Sans hunter's mark this would be about 20, and I'd be really struggling to consider him a viable skirmisher. He can't tank much so manoeuvrability, respectable damage and the occasional stunt is all he offers. The sorcery mostly comes in for special damage, utility powers and the occasional shield.

This causes a bit of a problem for me in terms of spell selection, because it feels like a spell having Concentration requirement is pretty much a dealbreaker for me. I believe, in my heart, that I just won't cast it.

Castability Credence

I don't know how common this feeling is (I imagine it doesn't come up much), but I've encountered it with warlocks as well. Warlocks and rangers both rely on a similar Concentration-based mechanic to deal their extra damage, and so have the same vulnerability. Both also have limited spell selection and relatively few spells per day. The former means that selecting a spell you don't expect to use regularly is painful and risky if you could instead pick something you'll get lots of use out of. The latter means that recasting hunter's mark or hex is quite difficult, so losing Concentration to cast another spell and then being forced to recast it expends a very substantial chunk of your resources.

Basically, I get 9 spells per day. Hunter's mark takes either a high-level slot (not flippin' likely mate) or multiple low-level slots to maintain for a working day. I typically need at least a couple of cure spells, often an invisibility that happens before combat breaks out, and otherwise hurl combat magic around for AoEs or energy damage to tough targets. If I wish to cast, say, stinking cloud during combat, then here's what happens:

1. I lose part of the benefit of hunter's mark, thus partly wasting a spell slot
2. I gain the benefits of stinking cloud but cannot benefit from hunter's mark during this period, so my damage output drops significantly.
3. I can recast hunter's mark by expending another spell slot to regain the benefits

In other words, casting a Concentration spell has two additional costs: the loss of ongoing benefits, and the tax of an extra spell slot to re-cast the hunter's mark I usually have going.

I've got to admit, I was slightly confused by the decision to make this damage a spell effect when rogues can quite happily get extra damage from mundane abilities. However, it keeps rangers in line with warlocks and paladins, and prevents annoying players from trying to stack those abilities, so fair enough. The downside is that the ranger's damage output has some odd vulnerabilities, like the fact you can run out of magic and become unable to do extra damage any more, or get punched so hard you lose Concentration and your bonus damage goes away. This is of course more likely in a melée character; it's less of an issue for the warlock.

I suppose, from a certain point of view, the confusing thing is that they didn't add an equivalent mechanic for the rogue to keep everything in line.

Essentially, this introduces two new decisions into the equation:

1. during play: is this specific situation worth not only spending an action casting Concentration Spell X, but also partially wasting a spell I previously cast from a small pool, and losing the substantial benefits of hunter's mark for its duration, and having to expend a third spell slot to regain those benefits later?
2. during levelling: will situations of type 1 arise sufficiently often that it's worth investing in this spell rather than fireball?

Obviously in this specific situation I'm choosing sorcerer spells, but a similar thing happened last level when I bumped my ranger up. I took longstrider in the end because it doesn't require Concentration, whereas I couldn't really envision many situations where I'd want to cast fog cloud or any of the other options. I like the idea of using fly or fear, but how often would I actually do that rather than run some numbers, grimace and keep punching people?

It's particularly frustrating because I actually don't use Charlie's spells as much as I'd like (it makes the sorcerer part of him take a definite back seat). At present, other than cure wounds, he can use invisibility to sneak around, shield in emergencies, and I've pulled earth tremor a couple of times with limited success.

What I'd really like is for his spells to offer things he can't do just as effectively by hitting people. Unfortunately I don't feel like many of them meet that credence test. There's virtually no point taking any of the battlefield control spells, because especially given they don't last that long nowadays, you're giving up a lot by sacrificing bonus damage for that, and I doubt I'd cast them. I can't see any of the lesser-utility spells, like major image, being worth it.

So basically, for a spell to be worth choosing, I have to think I'd be likely to find it more useful in combat than maintaining the bonus damage I'd otherwise deal - perhaps when I couldn't easily attack in melée, or if the spell would lock down a group of enemies. Or, it needs to provide substantial out-of-combat benefits.

I'll probably end up taking something I think might see out-of-combat use, although I'm a bit wary of those since we have a wizard (and of course, anything sorcerers can cast, wizards can also cast). Maybe alter self, though a 2nd-level choice is a waste, or fly for adventure segments.

Anyway, I thought someone else might find this little scrawl offers some psychological insight, so there you go.