Neith Bai Yeong, Rock or Vivica. Zulag, Obakan or Grimble

Hi, there:
Never though I was going to have this problem. Information to consider:
1 I’m f2p. I have already overrun my luck. Probably no more shiny heroes for me.
2 My roster:

Yellow: Drake Fong +14, Joon 4/80. The listed 5☆ on the title. Mist +17, Wu Kong 4/70, Chao 4/70, Danzaburo 4/22, Hu Tao 3/60, Costumed Li Xiu 1/1.

Purple: Ursena +14, Domitia 3/36 (soon to be 4/80). The listed 5☆ on the title. Costumed Ridgard (1 4/70, 1 3/60, 2 1/1), Costumed Tiburtus (1 4/70, 1 1/36), Gafar (1 4/70, 1 1/1), Proteus (2 +17), Merlin 3/60, Sabina 3/60.

Red: Marjana +14. Puss and Anzogh 2/60, Azlar 1/1, Kaghan 1/1, Noor 1/1. Costumed Bold (2 4/70, 1 1/1), Gormek 4/70, Kolen 4/70, Kelile (1 4/70, 1 2/48).

Blue: Magni +14, Thorne 2/60, Ridgard 1/1. Kiril ( 1 4/70, 2 1/1) Costumed Sonya (1 +14, 1 2/34), Boril 4/70, Agwe 3/60.

Green: Costumed Caedmond (1 +16, 1 4/70), Costumed Little Jon 4/70, Costumed Skiteskull 4/50, Costumed Melendor (1 4/70, 1 1/1), Kashreek 4/70.

3 My preferences:
Tired of raiding, cup dropped to gold recently (from low diamond/high platinum).
I like war, tend to go mono to be able to take down the 4200+tp teams.
I like attaking titans, though recently tired.
I like events, completing, not competing.

Purple - Obakan while not totally terrible, isn’t that great. Domitia is much better. Zulag comparable to a C. Rigard, which you already have and Grimble is niche as he’s only really used as a minion destroyer.

IMO I would recommend going with Grimble and Vivica. Vivica is a better Healer than Zulag since her effect is immediate, she debuffs and give extra protection. Grimble because minions are exploding everywhere now and he can help with that.