Are there any solid tactics for dealing with demons other than yelling "for the Old Ones" and charging right in as although I have never fought demons I was shocked at the repeated claims that they're broke over the course of a 3k battle as it consists of plaguebearers, 50 horded blood letters, juggernaughts, Flamers, horrors a great unclean one and the skulltaker and a couple of heralds for his units. It this just hype or are they really that bad.
Daemons are very tough, it's true, but not invincible. They take a different approach to beat. Their greatest strength is that they don't really have any weaknesses- a mixed god list will have an answer for any situation, and their special characters are sickeningly under-priced for what they can do. Be that as it may, as Lizardmen, we have some good advantages to help us. I've faced everything you mentioned in that Daemon list at some point or other, so here's how I would deal with each: Plaguebearers- Not as bad as they used to be; their herald gives them regeneration, which doesn't stack with their ward anymore. Hit them with fire, or just kill the herald. In fact, that goes for every core choice in this army. Kill their Heralds! They do have poison attacks, so be careful. On a side note, if they run Epedimius, when Nurgle followers make kills he will add bonuses like making poison work on 4+. This helps our skink's poison, too, so take your advantage. Bloodletters- A glass cannon if there ever was one. They're fast, hit hard, and have killing blow, but die easy. With a horde like that, salamanders will have a holiday, and razordons will actually be useful as well against smaller units. Remember, the whole army is immune to psychology, so you won't panic them; just soften them up as much as possible and then nail them in combat. Everything Khorne has some degree of magic resistance, which stacks with the 5+ ward that all daemons get. Go for hexes and shooting for max effect. I like to confront them with skink/ kroxigor blocks. The skinks usually get wounded on 2's against everything anyway, so let them soak up those nasty attacks and take advantage of the new shield parry save. Don't use Cold Ones, as killing blow will eat through the high priced cavalry in a bad way. Their herald gives them hatred, and can easily have max armor if he's on a mount. Very nasty. Bloodcrushers- I assume this is what you mean by Juggernauts. They're scary, but hugely expensive at 70 points each and only T4. Treat them like Bloodletters, just a little more carefully. Flamers- One of the best skirmishing units, period. They can get off an insane number of shots, and they're pretty tough to kill, too. They come in units of 6 max, so try to pin them down somehow and outnumber them, or just get into combat with something else so they can't shoot. Do remember though that their close combat attacks are flaming as well, so if you're using the Life regeneration spell they can charge you to negate it, and let something else hurt your Temple Guard. Horrors- Meh. They have to use up dice from the pool now if they want to shoot, and they're soft in combat. They do channel however, and they're usually escorting a Tzeench herald which gives them a 4+ ward. Get them in combat, just keep your characters away if the unit contains the Changeling. Skulltaker- He's there for one reason: To kill characters and their mounts. He'll killing blow your carnosaur or stegadon in a challenge on a 5+, so keep them far, far away. Remember, he only has regular, non-heroic 6+ killing blow outside a challenge, so let the peons beat him down while your characters cower in the back. He's only got two wounds. Great Unclean One- It has a TON of wounds, likes to force toughness tests, and has a very, very nasty spell that makes almost all of your stats '1' if you're in base contact (It's his base spell). Oddly enough, he's not immune to poison himself, so skink him down and dispel his magic, and then wail away till he smooshes from combat resolution. A few other things... As much as taking out the BSB is important with any army, it's critical with Daemons. Their special banners have some truly horrible effects, so make it a point to remove it from the battlefield posthaste. Flamers aside, they don't have much of a shooting phase to speak of, and no war machines whatsoever (Unless you want to count Ku'gath, but he's like 650 points and he doesn't turn up too often). Remember this as you plan your list. I say try a game or two against the Daemons and judge for yourself how bad they are. I've got a winning record against them simply from learning from my losses and devising a better plan, rather than crying "Broken!" and complaining that they can't be beaten. Let us know how you fare against them!
This also may be obvious, but taking lore of light and EoTGs will also help a bit seeing as both are more effective when against demons.
Does the Standard of Sundering still make LoLight almost useless against Daemons? If so i'd prefer LoFire over it; it's your basic damage lore; in a previous game vs Daemons (albeit 7th edition) my Slann took out a unit of Seekers on the first turn with a single well-placed Fiery Blast. Don't just kill it, kill it with fire! Alternatively, if you know your main daemon opponents are Nurgle based (unlikely, as Nurgle is the least powerful) then make your list based around a Shadow Slann; nurgle's general low initiative means that any large plaguebearer hordes are easily dealt with using Pit of Shades. The best initiative of any nurgle daemon is 4 from the GUO, with nurglings having 3, heralds having 2 and bearers having a measly 1!
Yeah, it does, and I'm seeing a lot of it lately. You're at -2 to cast with whatever lore they declare to start with, and if that isn't bad enough any Light spells miscast on double 1's 2's and 3's- minus the irresistible force, naturally. If I could pick one item to permanently delete from Warhammer, it'd be either this banner or Ring of Hotek.