First of all, a quick note, as it looks like you're missing a couple useful Allies: Munda, Ambush Leader, Mina and Denn, Wildborn, and Munda's Vanguard (maybe) could probably replace some combination of Kor Bladewhirl, Makindi Patrol, Ondu Champion, and/or Coralhelm Guide.
If you're using Tazri as your commander but actually building around Zada's ability to buff your team, you have some pretty unique opportunities; not only do you have access to a whole bunch of spells that Zada decks can't play because they're not mono-red, you can also make use of Zada's predecessor -- Ink-Treader Nephilim! Yes, it breaks your tribal unity, but it also doubles your access to the Radiate effect (which, by the way, you could also play).
Also: clone spells! You already have Cackling Counterpart and Rite of Replication, but any single-target instant/sorcery that copies creatures does twice as much work as usual here, since it both gives you additional Ally ETB triggers and can be refracted with Zada/Ink-Treader -- so I'd recommend playing as many such effects as possible. Fated Infatuation, Heat Shimmer, Spitting Image, Stolen Identity, Tempt with Reflections, and Twinflame are all options here. Supplant Form gets special mention when used alongside Ink-Treader -- because the Nephilim targets everyone's creatures (not just your own), Supplant Form basically becomes Insurrection.
Actually I should really just stop here and suggest that you look up other people's attempts to build around Ink-Treader (for those who allow the Nephilim as honorary generals), which will be full of weird and fantastic tech for a deck focused on Zada whether or not you actually include Ink-Treader -- stuff like Wild Defiance or even Fiery Gambit (yes, it technically targets only a single creature) that hardly get played anywhere else but become absurdly good in this situation.
Just a quick heads up: Alesha cannot recur Spirit of the Labyrinth, as it has 3 power. Still a powerful hate effect, but it's pretty fragile without a reliable means of getting it back after it dies.
What a great concept! Tribute and will of the council are the perfect mechanics for this. (If only there were more playable cards with those mechanics...)
If it's not outside your budget restrictions, check out Painful Quandary!
If you're using Tazri as your commander but actually building around Zada's ability to buff your team, you have some pretty unique opportunities; not only do you have access to a whole bunch of spells that Zada decks can't play because they're not mono-red, you can also make use of Zada's predecessor -- Ink-Treader Nephilim! Yes, it breaks your tribal unity, but it also doubles your access to the Radiate effect (which, by the way, you could also play).
Also: clone spells! You already have Cackling Counterpart and Rite of Replication, but any single-target instant/sorcery that copies creatures does twice as much work as usual here, since it both gives you additional Ally ETB triggers and can be refracted with Zada/Ink-Treader -- so I'd recommend playing as many such effects as possible. Fated Infatuation, Heat Shimmer, Spitting Image, Stolen Identity, Tempt with Reflections, and Twinflame are all options here. Supplant Form gets special mention when used alongside Ink-Treader -- because the Nephilim targets everyone's creatures (not just your own), Supplant Form basically becomes Insurrection.
Actually I should really just stop here and suggest that you look up other people's attempts to build around Ink-Treader (for those who allow the Nephilim as honorary generals), which will be full of weird and fantastic tech for a deck focused on Zada whether or not you actually include Ink-Treader -- stuff like Wild Defiance or even Fiery Gambit (yes, it technically targets only a single creature) that hardly get played anywhere else but become absurdly good in this situation.
If it's not outside your budget restrictions, check out Painful Quandary!