Another creature that's very hard to design for. The two-ofs of each deck are the cards which summarize their strategy:

Terran: Marine and Siege Tank (activated abilities and morph)
Protoss: Zealot and Vortex (strong and few creatures, bounce/exile, resetting psi counters)
Zerg: Zergling, Hydralisk. 1/1 creatures, attacking, using those 1/1 creatures

But it's so hard to think of an ability for Hydralisk that both captures the feel of the unit and translates well as a game mechanic. Prowl was supposed to be the Zerg repeated mechanic but it's not being used now.

Ladies and Gentlemen, WE HAVE OUR ZERG ABILITY.

Hydralisk
Creature - Zerg [C]
Raid - ~ enters the battlefield with a +1/+1 counter on it if a creature you control attacked this turn.
2/1

Settled on this ability, similar to the "breakthrough" ability in the great designer search 2. Works wonderfully with all other Zerg cards, power level strong but not overly insane.

Edit: 2/2. Made immune to Firebats.

This card does not work in the rules framework. It triggers upon attacking, but there's not such thing as 'being blocked' at that point.

How about:

­: Hydralisk gets +1/+0 until end of turn. Activate this ability only once a turn and only if you control an unblocked creature.

That does work in the rules. is a bit weird, but it happens; the last printed card to get it is Haunted Plate Mail.

I don't think so. The phrase "Whenever ~ attacks and isn't blocked" is a common enough phrase in MTG and is phrased the same way - it's a combined condition, so the trigger goes on the stack during the blocking phase, not the attacking phase. :)

Previously :

Hydralisk
Creature - Zerg [c]
Whenever Hydralisk attacks and at least one attacking creature isn't blocked, Hydralisk gets +1/+1 until end of turn.
2/2

• Changed because of too many questions about blocking timing, about misunderstanding the card, etc.
• TEST THIS CAREFULLY. Very aggressively costed. It's essentially bloodthirst that only triggeres on combat damage, and the most comparable one is Stormblood Berserker. Bloodthirst creatures are usually below curve when cast normally and slightly above curve when triggered. Here it's on curve when cast normally and pretty damn good when triggered.