[Spheres of Power] Rituals' interactions with Mythic Archmage - help to optimize

[Van Silke]

This is a technical question of a player who wants to make the best out of his situation - with in-depth explanations. If you're willing to help, please stick around.

Hello there. Short version is, I'm a spherecaster who suddenly got a mythic tier, and I haphazardly chose Wild Arcana Archmage. I want to make the best of this thing.
I'm sorry in advance to raise standards, but it's best if I got opinions of people who are familiar with both vanilla Pathfinder magic, Mythic Adventures, and Spheres of Power and its variant spellcasting option of Rituals.


Starting off with a little context: I'm a level 5, elven neutral-evil Incanter (alternate racial trait: darkvision, backstory traits: Reactionary and Theoretical Magician; feats: Improved Initiative, Ritual Casting, Craft Wondrous Item), with a "dark, paranoid necromancer with mental issues" theme. I've selected drawbacks of Somatic Casting (1) and Spell Focus. I've traded my extra feats for class features of Channel Negative Energy and Sphere Specialization: Death. Because it doesn't hurt me, I've got a mithral shirt and darkwood heavy shield.
My current talent list is as follows:
Dark: Clinging Darkness, Feed on Darkness, Step Through Darkness. Planned: Black Lung, Snagging Darkness, Mass Meld, Clearsight, Thick Darkness, Dark Slaughter
Death: Drain (Ghost Strike), Lingering Necomancy, Empowered Necromancy, Expanded Necromancy, Permanent Undead. Planned: Greater Ghost Strike, boosting Greater Reanimate
Divination: only base

Because it's a homebrew campaign, our GM had us fight a genie, and upon defeating it, we've ascended into our first mythic tier. I chose Archmage with Wild Arcana ability, as well as Crafting Mastery and Mythic Crafter (since I'm the crafter of the party). Later on, I'm planning to take Dual Path for Hierophant's Inspired Spell to gain access to divine rituals, or Marshal's Advance to help my small army of undead move along.

Because these things are normally totally incompatible, our GM ruled as such for using Wild Arcana:
*As a swift action I may use any sphere ability as if I had one additional talent of my choice (chosen upon casting) with no spell point expenditure. I can use it on any sphere I know, as well as apply any metamagic feat to it and increase the effect's caster level by 2.
*As a swift action I may use any arcane ritual of 0- and 1st level. I must spend written amount of time on casting any higher-level ritual, but I've still got access to them. As far as I know, material costs still apply, but it might change.

My current tactics with using Wild Arcana are to get early access to some of Dark sphere debuffs (Snagging/Black Lung or something else) but I'm at loss as to how should I use these rituals to full effect.

My question to you is - how would you use it, how would you abuse it, what spells would be the most useful to cast in form of a ritual? For the record, we have no vanilla casters in the party.