Astrid is a half tank warrior. Her Ultimate will get more powerful when she is running low and it will make her invincible. So choose wisely whenever you see Astrid is activating her ultimate.
Abilities
Passive - Bladed Guardian
When Astrid's HP falls below 80%, she gains a shield that absorbs HP for four seconds. The shield effect has a 24-second cooldown and will be reactivated when Astrid takes damage again.
While the shield is active it deals magic damage to surrounding enemies. Cooldown is reduced by 3 seconds everytime Astrid hits an enemy hero with an ability or normal attack and by 1.5 seconds everytime she hits an enemy minion or monster.
Astrid's normal attack can reduce the cooldown of the shield. When she's running low, instead of seeking an escape it might be better to attack the enemy and trigger the shield to gain extra protection.
Ability 1 - Spin Slash
Astrid swings her mighty sword around dealing physical damage to surrounding enemies. If she hits an enemy hero, Astrid's attack speed will increase by 2% and an additional 5% for every other hero hit for 3 seconds.
Astrid's core ability to deal damage try to hit as many targets as possible to maximize attack speed. It is highly recommended to level Spin Slash first.
Ability 2 - Fearless Charge
Astrid charges forward dealing physical damage, slowing enemy movement speed by 2% for 1.5 seconds, and decreasing target armor by 30% for 4 seconds. Her next normal attack will be a critical hit and will reduce Fearless Charge cooldown by 1 second. This effect cannot stack.
Astrid's second ability actually enables her to charge forward twice. The critical hit following the fearless charge can also let her charge forward for a short distance. It can use the target's position to get through thin walls.
Ultimate - Dire Blow
Astrid powers up and becomes immune to all damage for 2 seconds. After 1.5 seconds she swings her sword dealing physical damage.
For every 2% of her own max HP, she has lost she will deal 1% more damage. The ability also slows the enemies movement speed for 1.5 seconds.
If the enemies HP is higher than Astrid's the ability also stuns the enemy for 1 second. Don't rush to release Dire Blow because it will get more powerful with stun effect when Astrid is running low.
Try to release it when Astrid is in the center of the enemy fire. The invincible effect will make it a good trade with enemy heroes and towers.
Astrid's common combo is to use the second ability to quickly move, use the first ability to deal damage and boost attack speed followed by the critical hit to slow down enemy targets. Finally, use the ultimate to complete the skill. 2 + 1 + A + 3
In the early game, Astrid can either choose jungling or use the first ability to quickly clear the waves and level up. Since Astrid's control ability is not very stable, obtaining Might Golem is a good choice to increase the chance.
In the late game, invincibility can ensure Astrid to initiate the attack. First focusing on enemies squishy targets then after attracting enemy teams firepower, Astrid can unleash the ultimate to avoid all damage.
The normal attack should be frequently used for Astrid as it will reduce the cooldown of both the shield and second ability. In this way, she can definitely be a good killer.
Lore
"i will become your sword and cut through thorns for you."
When Astrid bent the knee in front of Thane, and to take her vows, she was not yet 18. But as the bearer of the famous sword "Embertrail" and the legitimate heir of the Duke of Roses, Astrid took up the mantle imposed upon her by history. She raised the Flaming Rose standard high and stood next to Thane, showing the world the allegiance of an old noble house to the new king.
With Astrid's support, the doubts that followed Arduin's death eventually quieted and people started to reflect on the failure of Arcticia. Even though Astrid's father and brother died in the war, she did not pay any mind to gossip and whispers from the Temple. Her support in Thane's ascension provided some much-needed stability in times of conflict.
In return, Thane awarded the unprecedented honor to the Rose family, and Astrid became the kingdom's first duchess. But before she could do anything with her territory, dark powers returned with Taara leading the charge. Arduin and Mina, corrupted by dark power, were spotted among their ranks.
Astrid knew that the murderous leader was the one responsible for her father's and brother's deaths. She could not wait to join the battle and avenge them, but Thane gently stopped her. Looking at the girl with affecting and care, Thane Said, "You have done enough for me. I shall care of the rest."
"My lord, I don't think you understand," declared Astrid with her head held high, showing resolve that no man of her age would ever possess. "I took my vows as a knight. Dukes can wait in their castles for news of victory, but knights must charge into battle!" With that said, she unclasped her crimson mantle, unsheathed Emertrail and led her knights to war.
"My resolve will never waver!"