A slight difference between War Frenzy and Gamma Booster though.
War Frenzy loses a stack when the character attacks/counters etc. If Cap gets hit with shield guard up, he'll gain a stack, counter and then down 1 stack.
Gamma Booster stacks stay regardless of character attacking/counters etc. If Cap gets hit with shield guard up, he'll gain a stack, counter. Gets hit again, go up another stack, counter even harder.
The other difference is that if Gamma Booster stacks wear off from duration to 0 stacks, the stacks are not built anymore and needs to be re-applied with the gadget.
War Frenzy stacks still build up even at 0 stacks because it comes from Hulk's Warbringer passive.
Triple ThreatNightcrawler's L9 (the name of which escapes me right now).
Sudden support boost my stats from 579 to 859 (+280 stat buff) until my next turn for 220 stamina (generalist trench coat filled with chaotic iso-8 at level 114). It's also increasing the damage I deal during counter-attacks/avenger follow up attacks and the 2 turn cooldown start when you activate it so you can use it very often.
I like to use sudden support with curative reach to fully heal my party, saving me team restore packs and other heroe's energy for other actions. If everyone is fine, I use it with the Mindkiller to destroy any ennemy with less than 3.5k hp (664-800 damage with 60% crit chance turn into 1320-1592 damage with 81% crit chance with sudden support )
I'm discovering how much Sudden Support rocks with Mindkiller + Scroll of Melsalam. I have a disctinct advantage using Spiderman + SW over CA + SW teams now.
The damage increase Sudden Support gives is actually quite high, slightly less than CO. Sudden Support will also increase your accuracy, so there's that. But Sudden Support won't double your attack damage, which is where CO wins.