How to Build Isaac?

Isaac's build is dictated by his use against Osh, since it is his main strength. Maestro leaves more freedom and therefore does not need to concern you: an Isaac optimized for Osh will be as good as he needs to be for Maestro.

Summary

  • Artifacts 118-0-130

  • Ascension V

  • Tree of Wisdom 49 min

  • Skins: agility only

  • Glyphs: agility, health, armor

  • Pet: maxed Oliver (levels and stars)

Health

Isaac tends to die pretty fast against Osh, and when Isaac dies, the team dies! So you really want him to have as much health as possible. Moreover it will make him ult more often by absorbing more magic damage.

In practive this means tree of wisdom 49, ascension V and a maxed Oliver patronage! Because of that I even advise making Oliver your first absolute star pet

Armor Penetration

You should give him as little penetration as possible without neglecting the rest. No skin, no book artifact.

This is because you do NOT want him to kill the spheres until he has gained four artifact buffs. Even if you just want to use Jhu (see below), this will still ensure a greater uptime with 3+ artifact buffs.

Weapon Artifact

I advise to pick 118.

Jhu with Vex needs at least three artifact stacks of level 115, Cornelius needs four of level 114, Lara needs three of level 121 (sometimes less, when she provides her own buff).

As explained above, armor penetration is dangerous. Should we go for 121? We know you can safely go as high as level 118 at least (the former level required by Cornelius). 121 is not very far but 2k more penetration will greatly improve Isaac's damage against the spheres after just three ults. I chose to stay at 118, chose at your own risk!

Of course, for pvp, it would be better to have a higher level. But in practice it would rarely make a difference because mages have a low armor anyway. So a single stack should give enough penetration to the whole team. Even if they had an armor artifact on their side, Isaac ults fast enough to quickly gain a second stack, much faster than the enemies can increase their armor.

Agility and Attack Power

As long as you have not given him penetration, you should be relatively fine with attack power. I advise maxing his agility for armor, but not touching his physical attack skin and glyph - or just a bit.

Mine sits at 88k attack, and I am happy with him.

What if you screwed up and gave him penentration? Then no attack power for you, and you may have to sacrifice his agility (more premature deaths against Osh) or renounce high-scores.

Magic Defense

Magic defense has zero effect when below the enemy penetration (see zerodef). And Isaac's magic def is way, way, below Osh's penetration. So there are two cases:

  • Harmful if you have Cornelius in your team and you raised his weapon artifact (magic defense)

  • Useless in all other cases

What about pvp? Magic defense slows down how fast you ult, in exchange for some survival. The pros and cons are circumstantial and debated among the community, but I personally advise you not to raise it.

Armor

Yes. Useless for Osh and Maestro, since you will never get enough to have a non-zero effect, but important for pvp.

Calculations

Osh has 168,833 armor

  • Jhu has 37,955 armor penetration, Vex brings a 9,958 buff, so he needs 120,920 more

  • Lara has 25,980 armor penetration, Vex brings a 9,958 buff, so she needs 132,895 more

  • Cornelius has 10,650 armor penetration, so he needs 158,183 more

  • Isaac can have up to 40,301 armor penetration

Isaac's artifact gives:

  • level 113: 39,438

  • level 114: 40,038

  • level 115: 40,641

  • level 118: 42,474

  • level 121: 44,346

  • level 130: 50,190