You have probably seen the older builds of MK, which stack Power duration (PD) to keep up the avatar state. Sadly avatar state does not stack with power duration anymore, making it more difficult to keep up avatar state. Combining this with the fact that spirit on hit has a internal cooldown leads to difficulties in avatar state uptime.

Thus comes in play this build! With this build you can comfortably do cosmic trainyard and solo cosmic patrols with ease. 

The core of this build is

The passive generates 30 spirit per second. Combinig it with DP Team-up gives us 35 spirit per second.

 Increases the duration of buffs and bleeds inlc. the Electro artifacts passive!

 100 spirit per use and dmg shield (incl. one-shot protection) for 3 sec. Watch out for the avatar state buff in the buffs          menu. If the timer is at 0 sec, press your medikit button for the shield. This will protect u until u can use ur avatar state again in 1 - 2 sec. Keep in mind that the Electro artifact does not have 100 % uptime, meaning that u sometimes can/have to use ur ranged abilities to bridge the downtime. 

Aim to get 1200 max spirit (Konshu's Favor). Every 200 points gives us 1 extra second of avatar state.

Further spirit generation sources that help are: +3 spirit on basic attack (pet), 5 spirit on power hit (catalyst), moon staff (3.8 spirit)
But they won't have a big impact :(

Also important

 Adds a source of vulnerability.

 Gives us a huge stat increase.

Artifact alternatives

Elektra's Mask Elektra artifact is still BiS for Dummy TTK but I don't recommand it for normal content bcs of summon aggro and uptime.

Advanced Circlet of Cyttorak  Can be used instead of Siege or Flag.

Dummy TTK pre-Elektra fix 1:17

Ultron TTK pre-Elektra fix 1:57