Concerns of The Deep? I'm Cubin'

Buy left to right
Healing Rite will upgrade into Rescue Beam
Mystic Burst will allow you to deal more damage to the enemy with Splatter (1), and Guardian Ward will allow you to keep your laning partner safe when they go in, or try to get out
Feel free to grab an Extra Starter for either more healing, or more damage.

Pick Restorative Locket if the enemy spam abilities
Healing Nova is more expensive but will allow you to heal multiple people
Extra Regen for more passive regen
Spirit Strike is to deal more damage with Puddle Punch (3).

Buy left to right
Use Rescue Beam one someone in The Cube (2) to pull them to you safely! Positioning is key, so always try to remain behind your allies rather than in front of them
Once you get Echo Shard, you'll be able to Double Cube your allies! Don't be afraid to grab another Active from the lists on the right.

If you find yourself dying a lot, or simply taking a large amount of damage, consider one (or more!) of those items.

Upon acquiring Alchemical Fire, you should always throw it at the enemy during any fight
You can consider some of the Alchemical Fire Debuffs items below to empower Alchemical Fire with various debuffs! Your allies will thank you! If you feel like Alchemical Fire will not be useful during your match (Too many flyers or too much mobility), skip it then consider one of the Debuff Actives or Support Actives to turn the tides of battle!

These will help your team take down strong opponents easily! Silence Wave, Curse or Focus Lens are recommended.

All of those items will trigger once an enemy steps on the fire of Alchemical Fire or when you hit them with Splatter (1)!

These actives can give your team a huge advantage during a fight or one specific enemy! If you didn't sell Guardian Ward, feel free to upgrade it!

These items are NOT part of the build but can be bought to create a playstyle that suits you more
Consider Healing Tempo if you have Healing Nova!