Ok maybe someone has already asked this, if so I apologize.
If I'm a wizard using a speli wich requires an attack roll, I roll a D20 + Spell attack modifier wich is: proficiency bonus +
your intelligence modifier. Ok suppose that I have INT 20 my roll, at level 17, will be: D20 + 11 (5 INT + 6 Proficiency), I'm trying to hit a Fighter with a Plate Armor (AC 18) +3 and a Shild (+2) +3 for a total AC of 26, so I can hit him only with a 16+ roll, meaning I've only 25% probability to hit, if he had a +5 set (30 AC) I'll hit him only with a 20 5% probability. The same is valid for monster with the same lavel of armor and I could have easily wasted one spell slot. Now another warrior class could have a +3 or +5 weapon meaning 5(STR/DEX) + 6 (Proficiency) + 3/5 (Weapon) = 14/16 + D20, so in the first case he'll hit with 13+
40% probability, in the second 15+ 30% probability.
If this are the numbers, we still have no official list of magic items, do you think is right? Or magic users need something that gives them a spell attack bonus?
Thanks 
A fighter in plate armor, with a shield, is supposed to be really hard to hit. You might only have a 25% chance to hit, but so would another level 17 fighter trying to attack.
Magic bonuses only go up, as far as I know, to +3. Even that is only speculation, because the existing magic armors and weapons we've seen are only +1, and I don't believe that +1 shields are even canon yet.
As far as we know, the worst-case scenario might be that you have a 20% chance to hit this fighter in +1 plate with a shield, and your fighter buddy has a 25% chance to hit because he has a +1 sword.
well could the wizard have a wand spellfocus +3? or bracers of wizardry +3 that both add to his attack bonus?
i mean this is highly hypothetical both ways.
also maybe if the wizard knows the heavily armed fighter is hard to hit and damage with aimed things, maybe just cast something that the poor guy has to try and save against, and now your DC is at like 18-20 (whatever it would be) and that heavily armoured enmey will probly fail and take damage anyway.
also if we look at the also in terms of monsters, the adult red dragon with CR17 is only 19 AC,(the highest in the DM basic rules) so a fully magiced out defensive bad guy would surely be hard to hit with aimed things, but unless he had a dex of 16+ (unlikely) he would fail magic saves and take full damage every time (in my estimate). the hobgoblin and knight have 18 AC and both could wear magic armour, but it would change the CR for sure, also both have very low dex bonus's at +1 and +0 respectively, but yeah i think this is why there are saving throw spells, advantage, and other things to help you hit.
use a spell that doesn't require you to roll an attack to hit. Wizards have lots of them.
silentdante wrote:
Dane_McArdy wrote:
Kaang wrote:
Kaang wrote:
well as far as cantrips, the wizard could use Acid Splash, it is just a save (but low damage at d6 base), poison spray is a con save, so the fighter might be ok at that, but it is d12 damage base,
and if the qizard does have spell slots, this is dependant on level, but remember, no matter the fighters AC, magic missile will always hit, so say the qizard casts magic missle as a third level spell, that would be minimum 10 damage max 25 damage.
but yeah in a straight up fight where the qizard could not stay out of melee range, he would probly always lose, unless he polymorphed the fighter and other things he would fail a save at, this also depends at what level you are considering the fight to happen at.
Kaang wrote:
Saelorn wrote:
Kaang wrote:
If you encounter an enemy that is wearing heavy armor, they very likely have a low Dexterity save. Throw a Fireball or Lightning Bolt, or better yet, since you are level 17 Disintegrate. He's hard to hit with spell attacks, but his Dex save is likely abysmal since characters wearing heavy armor usually forsake Dexterity. Casters have the option of being able to attack with effects that require saving throws, generally non casters do not have that luxury. This is why they get the benefit of having Archery Fighting Style, +1 weapons, etc.
Kaang wrote:
Why are you trying to kill that Fighter, anyway? He's on your team! Are you a team-killer?
To contribute to the discussion: Have we actually seen shields with bonuses to AC on them? There was one shield in the playtest, and there's one in the Hoard supplement right now. Neither have a bonus to AC. THey just have different properties that help in combat. Two examples aren't a lot to go on, but I wouldn't imagine we'll be seeing +X shields in this edition.
Or, if we do, then they'll have the same caveat as the other magic items: some items make players very powerful, and the combinations can remove any semblance of difficulty from the game. DMs probably shouldn't be giving players +3 armor and +3 shields at the same time, and they definitely shouldn't be giving them to monsters that wear plate.
For myself, I won't be giving out +X shields. I'd rather the shield give some bonus to something else. I love the Spellguard Shield form the playtest, for example. The one in Hoard is pretty nice, too. It has a bonus to AC, but only in certain circumstances, and only a +1. That's all you need on a shield in this system.
Saelorn wrote:
Which would basically make the wizard a fighter but with spells? Well, that would be a complete 180 from 4e I guess. lol
At level 17, you have a TON of spell slots. If you can't kill a single being with all of them.... then you don't need to kill that guy, obvs.
But, as for at will damage, as a wizard, you are going to want to have a good range of options. You will want to have an AC attack, and spells that target each Save. And some spells that will hit regardless of saves (Sleep). Cast a high powered Sleep spell on that fighter. And when he goes to sleep, melt his armor, sink him into the earth, shunt him into an alternate realm with no air, or whatever else you wanna do.
So yeah, there are plenty of options for the wizard to take out a fighter! Relying on you weakest abilities to take out the toughest class in the game is going to be difficult however, regardless of the equipment you or your target uses.