You gain the ability to come up with solutions under pressure. When you or another creature you can see within 30 feet of you makes an ability check or a saving throw, you can use your reaction to add your Intelligence modifier to the roll. You can use this feature a number of times equal to your Intelligence modifier (minimum of once). You regain all expended uses when you finish a long rest.
You achieve a profound understanding of how to use and make magic items: [+] You can attune to up to four magic items at once. [+] If you craft a magic item with a rarity of common or uncommon, it takes you a quarter of the normal time, and it costs you half as much of the usual gold.
You learn how to store a spell in an object. Whenever you finish a long rest, you can touch one simple or martial weapon or one item that you can use as a spellcasting focus and store a spell in it, choosing one 1st- or 2nd-level spell from the artificer spell list that requires 1 action to cast (you needn't to have it prepared). While holding the object, a creature can take an action to produce the spell's effect from it using your spellcasting ability modifier. If the spell requires concentration, that creature must concentrate. The spell stays in the object until it has been used a number of times equal to twice your Intelligence modifier (minimum of twice) or until you use this feature again to store a spell in an object.
Your skill with magic items deepens more: [+] You can attune to up to five magic items at once. [+] You ignore all class, race, spell and level requirements on attuning to or using a magic item.
You can attune up to six magic items at once.
You develop a mystical connection to your magic items, which you can draw on for protection: [+] You gain a +1 bonus to all saving throws per magic item you are currently attuned to. [+] If you're reduced to 0 hit points but not killed out-right, you can use your reaction to end one of your artificer infusions, causing you to drop to 1 hit point instead of 0.
You learn new ways to channel arcane energy to harm or heal. When either you hit a target with a magic weapon attack or your steel defender hits a target, you can channel magical energy through the strike to create one of the following effects: [+] The target takes an extra 2d6 force damage. [+] Choose one creature or object you can see within 30 feet of the target. Healing energy flows into the chosen recipient, restoring 2d6 hit points to it. [+] You can use this energy a number of times equal to your Intelligence modifier (minimum of once), but you can do so no more than once on a turn. You regain all expended uses when you finish a long rest.
Arcane jolt and steel defender become more powerful: [+] The extra damage and the healing of your Arcane Jolt both increase to 4d6. [+] Your steel defender gains a +2 bonus to Armor Class. [+] Whenever your steel defender uses its Deflect Attack, the attacker takes force damage equal to 1d4 + your Intelligence modifier.