这个2-tier啥意思？

650 - Level up a Light card
685 - Win Duels 5 times
720 - Win Guardian 2
755 - Seduce Light cards 3 times
790 - Open Silver Boxes 4 times
825 - Level up Light cards 5 times
860 - Win Guardian 5
895 - Have 2-tier soulbound Light Card
930 - Win Guardian 8
965 - Get 15 Rare Light card duplicates
1000 - Open chests in Duels 4 times
1035 - Win Guardian 12
1070 - Get 40 Common Light card duplicates
1105 - Spend 25000 Sun Essence
1140 - Have 3-tier soulbound Light Card
1175 - Get 10 Epic Light card duplicates
1210 - Win Guardian 16
1245 - Gain Polished stone
1280 - Have 4-tier soulbound Light Card
1315 - Get 4 Legendary Light card duplicates
1350 - Spend 45000 Sun Essence
1385 - Reach Master League III in Duels
1420 - Level up Rare Light cards 5 times
1455 - Have 5-tier soulbound Light Card
1490 - Open Nature Coffer
1525 - Gain Regular stone
1560 - Get 30 Rare Light card duplicates
1595 - Win Duels 20 times
1630 - Get 10 Epic Light card duplicates
1665 - Have 6-tier soulbound Light Card
1700 - Seduce Light cards 5 times
1735 - Have 4-star Northern card
1770 - Level up Light cards 20 times
1805 - Gain Pure stone
1840 - Have 4-star Gladiator card
1875 - Get 7 Legendary Light card duplicates
1910 - Spend 90000 Sun essence
1945 - Open Silver Box 7 times
1980 - Win Guardian 26
2015 - Open Golden Box 1 time
2050 - Soulbind Light Card 5 times
2085 - Open Nature Coffer 3 times
2120 - Win a prize in the Summer Weeks Tournament
2155 - Open Nature Coffer 6 times
2190 - Gain Radiant stone
2225 - Level up Light cards 15 times
2260 - Get 10 Legendary Light card duplicates
2295 - Have 4-star Demon Hunter card
2330 - Have 8-tier soulbound Light Card
2365 - Have 4-star Monk card
========== Phase 3
8000 - Level up Light cards 25 times
8105 - Win a prize in the Summer Weeks Tournament
8210 - Open Arcane Coffer
8315 - Gain Flawless stone
8420 - Open Golden Box 4 times
8525 - Gain 100000 Sun Essence
8630 - Have 5-star Northern card
8735 - Open Nature Coffer 10 times
8840 - Open chests in Duels 25 times
8945 - Have 5-star Gladiator card
9050 - Get card duplicate from Wheel of Fortune
9155 - Have 10-tier soulbound Light Card
9260 - Have 5-star Demon Hunter card
9365 - Gain Royal stone
9470 - Have 5-star Monk card
9575 - Win Guardian 50
9680 - Open Legendary Chest in Duels
9785 - Have 5-star Paladin Square card
9890 - Open Arcane Coffer 3 times
9995 - Have 10-tier soulbound Light Card
10100 - Have 5-star Phoenix card