Unknown summoner icons?

Question

I've came across some summoner icons that I seem to not have myself.

Where an how can I get those? (Talking mostly about the one from superari and hotrod in the screenshot.)

Answer 1

These are new summoner icons introduced for the League of Legends Halloween Event (I think it's called the Harrowing). These icons are earned depending on the amount of RP that you purchase within a designated time period.

• Tier 1 (any RP amount): Spiteful Specter
• Tier 2 (1,000+ RP): Baleful Grasp plus Tier 1
• Tier 3 (2,500+ RP): Death Mask plus Tiers 1-2
• Tier 4 (5,000+ RP): Deadfall Treant plus Tiers 1-3
• Tier 5 (10,000+ RP): Vengeful Wraith plus Tiers 1-4

Official link here

Answer 2

The answer above is correct, but the summoner icon to the right was unlocked during the League of legends championship.