[quote=@Behemoth542]
[color=7FFF00]>[/color] [b]Sonic Pulse:[/b] [i][color=yellow](Cost: 5)[/color] Sigma launches a powerful sonic pulse towards its enemies, which deals damage equal to Sigma's [color=red][b]ATK[/b][/color]. Entities affected are [b]stunned[/b] for a turn[/i]
[/quote]
With sonic-based attacks I'm thinking of allowing them to partially bypass an opponent's armour. If you increase the cost of this ability to 6 Energy then any target hit by it will only be able to use [sup]2[/sup]/[sub]3[/sub] Defence when countering it. If you increase the cost to 8 then the target will only be able to use [sup]1[/sup]/[sub]3[/sub] Defence.

You could even choose to take the ability with variable strength, so SIgma could save Energy when attacking lightly armoured targets, or ramp up the power to take down tanks.

[quote=@Behemoth542][color=7FFF00]>[/color] [b]Overload:[/b] [i][color=yellow](Cost: 1)[/color] For three turns, Sigma gains triple [color=gold]energy regeneration[/color] per turn, and always acts first. After this takes effect, Sigma is stunned and drained of all its [color=fff200]energy.[/color][/i]
[/quote]
I was going to say this would be too powerful an ability, but having done the maths I can't see how the ability would actually benefit Sigma with his 15 Energy cap at the moment.

Even if you were burning through abilities, I'd see a typical chain of events running something like:
[hider=Round Breakdown][indent]With [i]Overload[/i]							Without [i]Overload[/i]
[b]Round 1[/b]
[indent]15 Energy							15 Energy
[i]Overload[/i] = -1 Energy					[i]Incendiary Rounds[/i] = -3 Energy[/indent][b]Round 2[/b]
[indent]+1 Energy = 15 Energy					+1 Energy = 13 Energy
[i]Incendiary Rounds[/i] = -3 Energy			[i]Bullet Barrage[/i] = -4 Energy[/indent][b]Round 3[/b]
[indent]+3 Energy = 15 Energy					+1 Energy = 10 Energy
[i]Bullet Barrage[/i] = -4 Energy				[i]Sonic Pulse[/i] = -6 Energy[/indent][b]Round 4[/b]
[indent]+3 Energy = 14 Energy					+1 Energy = 5 Energy
[i]Sonic Pulse[/i] = -6 Energy					[i]Bullet Barrage[/i] = -4 Energy[/indent][b]Round 5[/b]
[indent][i]Overload[/i] ends = Energy 0				+1 Energy = 2 Energy
Sigma Stunned						Sigma attacks[/indent][b]Round 6[/b]
[indent]+1 Energy = 1 Energy					+1 Energy = 3 Energy
[i]Overload[/i] = -1 Energy					[i]Incendiary Rounds[/i] = -3 Energy[/indent][/indent][b]Result[/b]
[indent]1 [i]Bullet Barrage[/i], 1 [i]Sonic Pulse[/i], 1 Attack			2 [i]Bullet Barrage[/i] (1 Incendiary), 1 [i]Sonic Pulse[/i][/indent][/hider]
The only difference is that Sigma's attacks would happen first in the chain of events, rather than in the order they get posted as I'd normally action them. While that would be beneficial to you, it could mess up the other players' plans if Sigma manages to eliminate an opponent they were targeting for their own attack.

While I wouldn't stop you from taking the ability as it is, I'd recommend changing it to something like:
[indent][b]Overclock:[/b] [color=yellow](Cost: 3)[/color]
[indent]Overclocking his processor Sigma moves and acts faster. For two turns, Sigma may trigger two actions or abilities per round instead of the usual one and Sigma's attacks and abilities are dealt with before any other actions in the round. On the third turn Sigma's power is drained, reducing its Energy reserve to 0 and causing it to be [i][b]Stunned[/b][/i] for a round, but for two turns after that it gains the [i][b]Reboot[/b][/i] status effect, trebling its normal Energy regeneration as its systems reset.[/indent][/indent]