Active: Arctic Blast - emits a wave that freezes everything around the owner, slows enemy heroes by 40% for 4 seconds, and deals 200 AOE damage. It has a radius of 719 and a small 30 seconds cooldown.
Passive: Freezing Aura, which reduces the enemy's attack speed by 25% and weakens their healing, vampirism, and health regeneration. Before patch 7.20, Freezing Aura's passive would break through Black King Bar, but not anymore.
There are only two items in the side shop that grants 15 armor points. Shiva's Guard doesn't provide as much armor manipulation as Cuirass. Cuirass reduces the armor of enemies by five and increases the armor of allied buildings and heroes by 5 points. However, increased by 30 attacks from Cuirass, Shiva's Guard quickly interrupts. Shiva's Guard also passively weakens illusionists: up to 640 damage to Terrorblade illusions, 700 damage to Naga Siren illusions, and 1300 damage to Phantom Lancer illusions.
Few words on active abilities. Arctic Blast doesn't deal a lot of damage; meanwhile, it expands mass magic damage in a large AOE. Frost wave is also a fantastic nuke that grants additional vision, so your team can easily find the enemy hero behind the trees or on the high ground. Moreover, you can catch Tinker, Hoodwink, Broodmother, and other mobile heroes very effectively. Keep in mind that you can Rearm Arctic Blast on Tinker. That's how you can deal serious magic damage in the 1000 range (AOE).
First thing first, Shiva's Guard is bought specifically against heroes, not for. However, there is an exception when the hero receives special bonuses from purchasing Shiva's Guard. Silencer will get more intelligence damage, and Outworld Destroyer boosts his mana pool - this is also a kind of special bonus. SG is also great for heroes who find themselves in the center of the battle: Leshrac, Tidehunter, Death Prophet. In addition, this artifact is suitable for high-rate Int hand-damage personages, such as Invoker or Nature's Prophet. Heroes who purchase Radiance also can stash Shiva's Guard - Bloodseeker, Alchemist, Necrophos. You can also observe how high MMR players quite often take Shiva's Guard for Medusa. A crazy experiment but also an unusual combination of items for such a hero.
Perhaps in future updates, there will be some fixes for this item; that is, they will reduce the radius or reduce the amount of armor received from this item. Therefore, you should expect some changes in the characteristics of this item or the price of SG.
It is worth noting that, despite the obvious focus on magicians, Shiva's Guard is an artifact that is purchased for characters that deal bonus intelligence damage. So, let's say, Timbersaw's pierced Shiva prevents enemies from escaping, allowing the "timber" to destroy them in a narrow space.
To my mind, Shiva's Guard is an artifact for the late game and is bought as a response to the enemy carry, who collects artifacts for attack speed and damage. The conditional timing for the purchase is 30+ minutes, while the item does not lose its relevance until the end of the game.