The Magnetic Pauldron (AKA: Tech Support)

Be advised, his build makes use of Tasha's Customized Origins from Fantasy Grounds.

Traditional tanking is a difficult job. While most tanks have no trouble taking a hit, it's much harder for them to ensure they're taking a hit in their ally's place. Most tanking abilities only give disadvantage to attacks against allies, and almost none of them will do a thing against a well-aimed fireball. The Magnetic Pauldron is designed to work around this weakness, and in the process, serve as an effective support character and blaster

Race: Custom Origin "Kobold" (Small, Darkvision, Draconic, Mounted Combatant)
Class: Artillerist 5/Order Cleric 1/Artillerist 19
Stats: STR 10, DEX 13, CON 14, INT (15+2), WIS 12, CHA 8
ASI: INT +1 and WIS +1 @4, INT +2 @9, Resilient (DEX +1) @13, Tough @17, CON +2 @20
Important Spells: Acid Splash, Fire Bolt, Scorching Ray, Healing Word

A rare build that kicks in at level 1, the magnetic pauldron lives up to its name first and foremost by literally standing on its allies shoulders and protecting them from harm. Mounted combatant, the key to this build, allows the user to take any attack aimed at their mount, and give their mount evasion while riding them. Your ally will need to be medium or larger for this to work (though IDRotFM implies you can ride another kobold), but this tradeoff will make you an exceptionally potent defender. Fire Bolt and Acid Splash are going to be your primary damage spells from the beginning to the end. The former is often considered superior, but as most dnd battles take place against multiple opponents, and artificer damage boost scale better with AoE spells, you might want to reserve firebolt for single monsters who are far away and harder to hurt. Level 2 gets you arcane infusions, so take enhanced focus and enhanced armor for decent boosts. 3 is where you become an artillerist, and this is where your tanking potential skyrockets. The Protection Cannon lets you grant yourself and the ally you're riding temp HP as a bonus action every single turn for an hour. It doesn't stack unfortunately, but it's a powerful defense ability. Note that although you can hold a tiny cannon, you don't need to in order to use it. As a result, keep it inside your bag so you don't need to give up your shield or wand. 4 gets you an ASI, and you're putting one of those points in WIS, so that you have enough later to multiclass into cleric. 5 gets you an arcane firearm, which boosts your spell damage, as well as scorching ray, which is extra potent in the hands of an artillerist, as RAW you add your bonus damage to each individual ray.

At level 6 we dip into order cleric, this might be a strange choice but believe me there's a reason. See, while the protection turret has insane defensive potential you won't need to use it every turn. Unfortunately, you can only have one turret out at a time until level 15 and the cost for switching is steep. As the artillerist's DPR is designed around using their non-protection turrets. What this means is, you're sacrificing your role as a blaster to use a support ability that you don't even need to use every turn. That's where the order cleric comes it. Voice of Authority lets you give your allies a free reaction attack whenever you target them with a spell, while also giving you great support spells like healing word, bless and heroism. This will let you do your damage with a cantrip, and then heal your rogue or paladin giving them a free attack to do massive damage with so you don't need to. Order cleric also gives you heavy armor proficiency, but don't bother with it. You need to be light enough for your allies to carry.

From here we're back to artificer and the rest is standard